Cardiotocography

Last updated
Cardiotocography
Kardiotokograf.jpeg
A cardiotocograph recording fetal heart rate and uterine contractions
ICD-9-CM 75.32
MeSH D015148
CPT 59050

Cardiotocography (CTG) is a technique used to monitor the fetal heartbeat and uterine contractions during pregnancy and labour. The machine used to perform the monitoring is called a cardiotocograph.

Contents

Fetal heart sounds were described as early as 350 years ago and approximately 200 years ago mechanical stethoscopes, such as the Pinard horn, were introduced in clinical practice. [1]

Modern-day CTG was developed and introduced in the 1950s and early 1960s by Edward Hon, Roberto Caldeyro-Barcia and Konrad Hammacher. The first commercial fetal monitor (Hewlett-Packard 8020A) was released in 1968. [2]

CTG monitoring is widely used to assess fetal well-being by identifying babies at risk of hypoxia (lack of oxygen). [3] CTG is mainly used during labour. [4] [5] A review found that in the antenatal period (before labour), there is no evidence to suggest that monitoring women with high-risk pregnancies benefits the mother or baby, although research around this is old and should be interpreted with caution. [6] Up-to-date research is needed to provide more information surrounding this practice. [6]

A study found that CTG monitoring didn't significantly improve or worsen the outcome, in terms of preventable child death, post birth mortality, of pregnancy for high risk mothers. But the evidence examined in the study is quite old and there have been significant changes in medical care since then. [6]

Methods

The display of a cardiotocograph. The fetal heartbeat is shown in orange, uterine contractions are shown in green, and the small green numbers (lower right) show the mother's heartbeat. Cardiotocography.jpg
The display of a cardiotocograph. The fetal heartbeat is shown in orange, uterine contractions are shown in green, and the small green numbers (lower right) show the mother's heartbeat.
Cardiotocography sound
Schematic explanation of cardiotocography: heart rate (A) is calculated from fetal heart motion determined by ultrasound, and uterine contractions are measured by a tocodynamometer (B). These numbers are represented on a time scale with the help of a running piece of paper, producing a graphical representation. Cardiotocography diagram.jpg
Schematic explanation of cardiotocography: heart rate (A) is calculated from fetal heart motion determined by ultrasound, and uterine contractions are measured by a tocodynamometer (B). These numbers are represented on a time scale with the help of a running piece of paper, producing a graphical representation.

External cardiotocography can be used for continuous or intermittent monitoring. The fetal heart rate and the activity of the uterine muscle are detected by two transducers placed on the mother's abdomen, with one above the fetal heart to monitor heart rate, and the other at the fundus of the uterus to measure frequency of contractions. Doppler ultrasound provides the information, which is recorded on a paper strip known as a cardiotocograph (CTG). [7] External tocometry is useful for showing the beginning and end of contractions as well as their frequency, but not the strength of the contractions. The absolute values of pressure readings on an external tocometer are dependent on position and are not sensitive in people who are obese. [8] In cases where information on the strength or precise timing of contractions is needed, an internal tocometer is more appropriate. [8]

Internal cardiotocography uses an electronic transducer connected directly to the fetus. A wire electrode, sometimes called a spiral or scalp electrode, is attached to the fetal scalp through the cervical opening and is connected to the monitor. Internal monitoring provides a more accurate and consistent transmission of the fetal heart rate, as unlike external monitoring, it is not affected by factors such as movement. Internal monitoring may be used when external monitoring is inadequate, or if closer surveillance is needed. [9] Internal tocometry can only be used if the amniotic sac is ruptured (either spontaneously or artificially) and the cervix is open. To gauge the strength of contractions, a small catheter (called an intrauterine pressure catheter or IUPC) is passed into the uterus past the fetus. Combined with an internal fetal monitor, an IUPC may give a more precise reading of the baby's heart rate and the strength of contractions. [10]

A typical CTG reading is printed on paper and may be stored on a computer for later reference. A variety of systems for centralized viewing of CTG have been installed in maternity hospitals in industrialised countries, allowing simultaneous monitoring of multiple tracings in one or more locations. Display of maternal vital signs, ST signals and an electronic partogram are available in the majority of these systems. A few of them have incorporated computer analysis of cardiotocographic signals or combined cardiotocographic and ST data analysis. [11] [12] [13] [7] [14]

Interpretation

A typical CTG output for a woman not in labour. A: Fetal heartbeat; B: Indicator showing movements felt by mother (triggered by pressing a button); C: Fetal movement; D: Uterine contractions CTG Output.jpg
A typical CTG output for a woman not in labour. A: Fetal heartbeat; B: Indicator showing movements felt by mother (triggered by pressing a button); C: Fetal movement; D: Uterine contractions

In the US, the Eunice Kennedy Shriver National Institute of Child Health and Human Development sponsored a workshop to develop a standardized nomenclature for use in interpreting Intrapartum fetal heart rate and uterine contraction patterns. This nomenclature has been adopted by the Association of Women's Health, Obstetric and Neonatal Nurses (AWHONN), the American College of Obstetricians and Gynecologists (ACOG), and the Society for Maternal-Fetal Medicine. [15]

The Royal College of Obstetricians and Gynaecologists [16] and the Society of Obstetricians and Gynaecologists of Canada [17] have also published consensus statements on standardized nomenclature for fetal heart rate patterns.

Interpretation of a CTG tracing requires both qualitative and quantitative description of several factors. This is commonly summed up in the following acronym, DR C BRAVADO: [18]

Uterine activity

There are several factors used in assessing uterine activity.

The NICHD nomenclature [15] defines uterine activity by quantifying the number of contractions present in a 10-minute window, averaged over 30 minutes. Uterine activity may be defined as:

Baseline fetal heart rate

The NICHD nomenclature [15] defines baseline fetal heart rate as:

"The baseline FHR is determined by approximating the mean FHR rounded to increments of 5 beats per minute (bpm) during a 10-minute window, excluding accelerations and decelerations and periods of marked FHR variability (greater than 25 bpm). There must be at least 2 minutes of identifiable baseline segments (not necessarily contiguous) in any 10-minute window, or the baseline for that period is indeterminate. In such cases, it may be necessary to refer to the previous 10-minute window for determination of the baseline. An abnormal baseline is termed bradycardia when the baseline FHR is less than 110 bpm; it is termed tachycardia when the baseline FHR is greater than 160 bpm."

[19]

Baseline FHR variability

Moderate baseline fetal heart rate variability reflects the delivery of oxygen to the fetal central nervous system. Its presence is reassuring in predicting an absence of metabolic acidemia and hypoxic injury to the fetus at the time it is observed. [15] In contrast, the presence of minimal baseline FHR variability, or an absence of FHR variability, does not reliably predict fetal acidemia or hypoxia; lack of moderate baseline FHR variability may be a result of the fetal sleep cycle, medications, extreme prematurity, congenital anomalies, or pre-existing neurological injury. [15] Furthermore, increased (or marked) baseline FHR variability (see "Zigzag pattern" and "Saltatory pattern" sections below) is associated with adverse fetal and neonatal outcomes. [20] [21] [22] [23] Based on the duration of the change, increased (i.e. marked) baseline variability is divided into two terms: zigzag pattern and saltatory pattern of FHR. [20] [24] The NICHD nomenclature defines baseline FHR variability as: [15]

Baseline FHR variability is determined in a 10-minute window, excluding accelerations and decelerations. Baseline FHR variability is defined as fluctuations in the baseline FHR that are irregular in amplitude and frequency. The fluctuations are visually quantitated as the amplitude of the peak-to-trough in beats per minute. Furthermore, the baseline FHR variability is categorized by the quantitated amplitude as:

  • Absent – undetectable
  • Minimal – greater than undetectable, but 5 or fewer beats per minute
  • Moderate – 6–25 beats per minute
  • Marked – 25 or more beats per minute

[25] [ verification needed ]

Zigzag pattern of fetal heart rate

A Zigzag pattern of fetal heart rate (FHR) is defined as FHR baseline amplitude changes of more than 25 beats per minute (bpm) with a minimum duration of 2 minutes and maximum of 30 minutes. [20] However, according to another study, even a >1 min duration of the zigzag pattern is associated with an increased risk of adverse neonatal outcomes. [22] Despite the similarities in the shape of the FHR patterns, the zigzag pattern is distinguished from the saltatory pattern by its duration. According to the International Federation of Gynaecology and Obstetrics (FIGO), a saltatory pattern is defined as FHR baseline amplitude changes of more than 25 bpm with durations of >30 minutes. [26] In a recently published large obstetric cohort study of the zigzag pattern in almost 5,000 term deliveries in Helsinki University Central Hospital, Tarvonen et al. (2020) [20] reported: "ZigZag pattern and late decelerations of FHR were associated with cord blood acidemia, low Apgar scores, need for intubation and resuscitation, NICU admission and neonatal hypoglycemia during the first 24 hours after birth." Furthermore, the "ZigZag pattern precedes late decelerations, and the fact that normal FHR pattern precedes the ZigZag pattern in the majority of the cases suggests that the ZigZag pattern is an early sign of fetal hypoxia, which emphasizes its clinical importance." [20]

Furthermore, in the recent study of 5150 deliveries, the hypoxia-related ZigZag pattern was associated with cord blood acidemia, low 5-min Apgar scores at birth, and need for neonatal resuscitation after birth, indicating increased occurrence of fetal hypoxia in GDM pregnancies. [27]

Saltatory pattern of fetal heart rate

A saltatory pattern of fetal heart rate is defined in cardiotocography (CTG) guidelines by FIGO as fetal heart rate (FHR) baseline amplitude changes of more than 25 beats per minute (bpm) with a duration of >30 minutes. [26] [28]

In a 1992 study, the saltatory pattern FHR was defined by O'Brien-Abel and Benedetti as "[f]etal heart baseline amplitude changes of greater than 25 bpm with an oscillatory frequency of greater than 6 per minutes for a minimum duration of 1 minute". [29] The pathophysiology of the saltatory pattern is not well-known. [26] [28] It has been linked with rapidly progressing hypoxia, [30] for example due to an umbilical cord compression, and it is presumed to be caused by an instability of the fetal central nervous system. [26]

In a study by Nunes et al. (2014), [31] four saltatory patterns in CTG exceeding 20 minutes in the last 30 minutes before birth were associated with fetal metabolic acidosis. According to this study, saltatory pattern is a relatively rare condition; only four cases were found from three large databases.

In a study by Tarvonen et al. (2019), [21] it was demonstrated that the occurrence of saltatory pattern (already with the minimum duration of 2 minutes) in CTG tracings during labor was associated with fetal hypoxia indicated by high umbilical vein (UV) blood erythropoietin (EPO) levels and umbilical artery (UA) blood acidosis at birth in human fetuses. As saltatory patterns preceded late decelerations of fetal heart rate (FHR) in the majority of cases, saltatory pattern seems to be an early sign of fetal hypoxia. [32] According to the authors, awareness on this gives obstetricians and midwives time to intensify electronic fetal monitoring and to plan possible interventions before fetal asphyxia occurs. [21]

Due to a standardized terminology and to avoid miscommunication on CTG interpretation, it has been recently proposed in an exhaustive BJOG review of animal and human studies that terms such as saltatory pattern, ZigZag pattern and marked variability should be abandoned, and the common term "increased variability" should be used in clinical CTG guidelines. [33] [34]

Accelerations

The NICHD nomenclature [15] defines an acceleration as a visually apparent abrupt increase in fetal heart rate. An abrupt increase is defined as an increase from the onset of acceleration to the peak in 30 seconds or less. To be called an acceleration, the peak must be at least 15 bpm, and the acceleration must last at least 15 seconds from the onset to return to baseline. [35] A prolonged acceleration is greater than 2 minutes but less than 10 minutes in duration, while an acceleration lasting 10 minutes or more is defined as a baseline change. Before 32 weeks of gestation, accelerations are defined as having a peak of at least 10 bpm and a duration of at least 10 seconds. [25]

Periodic or episodic decelerations

Periodic refers to decelerations that are associated with contractions; episodic refers to those not associated with contractions. There are four types of decelerations as defined by the NICHD nomenclature, all of which are visually assessed. [15]

Additionally, decelerations can be recurrent or intermittent based on their frequency (more or less than 50% of the time) within a 20-minute window. [15]

FHR pattern classification

Before 2008, fetal heart rate was classified as either "reassuring" or "nonreassuring". The NICHD workgroup proposed terminology for a three-tiered system to replace the older, undefined terms. [15]

Updated 2015 FIGO Intrapartum Fetal Monitoring Guidelines

FIGO has recently modified the guidelines on intrapartum fetal monitoring, proposing the following interpretation: [36]

Benefits

According to the Cochrane review from February 2017, CTG was associated with fewer neonatal seizures but it is unclear if it had any impact on long-term neurodevelopmental outcomes. No clear differences in incidence of cerebral palsy, infant mortality, other standard measures of neonatal wellbeing, or any meaningful differences in long-term outcomes could be shown. Continuous CTG was associated with the higher rates of caesarean sections and instrumental vaginal births. The authors see the challenge in how to discuss these results with women to enable them to make an informed decision without compromising the normality of labour. Future research should focus on events that happen in pregnancy and labour that could be the cause of long-term problems for the baby. [7]

See also

Related Research Articles

<span class="mw-page-title-main">Heart rate</span> Speed of the heartbeat, measured in beats per minute

Heart rate is the frequency of the heartbeat measured by the number of contractions of the heart per minute. The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excrete carbon dioxide, but is also modulated by numerous factors, including genetics, physical fitness, stress or psychological status, diet, drugs, hormonal status, environment, and disease/illness as well as the interaction between and among these factors. It is usually equal or close to the pulse measured at any peripheral point.

Fetal distress, also known as non-reassuring fetal status, is a condition during pregnancy or labor in which the fetus shows signs of inadequate oxygenation. Due to its imprecision, the term "fetal distress" has fallen out of use in American obstetrics. The term "non-reassuring fetal status" has largely replaced it. It is characterized by changes in fetal movement, growth, heart rate, and presence of meconium stained fluid.

<span class="mw-page-title-main">Uterine rupture</span> Medical condition

Uterine rupture is when the muscular wall of the uterus tears during pregnancy or childbirth. Symptoms, while classically including increased pain, vaginal bleeding, or a change in contractions, are not always present. Disability or death of the mother or baby may result.

A nonstress test (NST) is a screening test used in pregnancy to assess fetal status by means of the fetal heart rate and its responsiveness. A cardiotocograph is used to monitor the fetal heart rate and presence or absence of uterine contractions. The test is typically termed "reactive" or "nonreactive".

A contraction stress test (CST) is performed near the end of pregnancy to determine how well the fetus will cope with the contractions of childbirth. The aim is to induce contractions and monitor the fetus to check for heart rate abnormalities using a cardiotocograph. A CST is one type of antenatal fetal surveillance technique.

<span class="mw-page-title-main">Chorioamnionitis</span> Medical condition

Chorioamnionitis, also known as intra-amniotic infection (IAI), is inflammation of the fetal membranes, usually due to bacterial infection. In 2015, a National Institute of Child Health and Human Development Workshop expert panel recommended use of the term "triple I" to address the heterogeneity of this disorder. The term triple I refers to intrauterine infection or inflammation or both and is defined by strict diagnostic criteria, but this terminology has not been commonly adopted although the criteria are used.

Postterm pregnancy is when a woman has not yet delivered her baby after 42 weeks of gestation, two weeks beyond the typical 40-week duration of pregnancy. Postmature births carry risks for both the mother and the baby, including fetal malnutrition, meconium aspiration syndrome, and stillbirths. After the 42nd week of gestation, the placenta, which supplies the baby with nutrients and oxygen from the mother, starts aging and will eventually fail. Postterm pregnancy is a reason to induce labor.

Placental insufficiency or utero-placental insufficiency is the failure of the placenta to deliver sufficient nutrients to the fetus during pregnancy, and is often a result of insufficient blood flow to the placenta. The term is also sometimes used to designate late decelerations of fetal heart rate as measured by cardiotocography or an NST, even if there is no other evidence of reduced blood flow to the placenta, normal uterine blood flow rate being 600mL/min.

<span class="mw-page-title-main">Vaginal delivery</span> Delivery through the vagina

A vaginal delivery is the birth of offspring in mammals through the vagina. It is the most common method of childbirth worldwide. It is considered the preferred method of delivery, with lower morbidity and mortality than caesarean sections (C-sections).

<span class="mw-page-title-main">Biophysical profile</span> Prenatal ultrasound evaluation of fetal well-being

A biophysical profile (BPP) is a prenatal ultrasound evaluation of fetal well-being involving a scoring system, with the score being termed Manning's score. It is often done when a non-stress test (NST) is non reactive, or for other obstetrical indications.

<span class="mw-page-title-main">Partogram</span> Composite graphical record of key data during labor

A partogram or partograph is a composite graphical record of key data during labour entered against time on a single sheet of paper. Relevant measurements might include statistics such as cervical dilation, fetal heart rate, duration of labour and vital signs.

An asynclitic birth or asynclitism are terms used in obstetrics to refer to childbirth in which there is malposition of the head of the fetus in the uterus, relative to the birth canal. Asynclitic presentation is different from a shoulder presentation, in which the shoulder is presenting first. Many babies enter the pelvis in an asynclitic presentation, and most asynclitism corrects spontaneously as part of the normal birthing process.

<span class="mw-page-title-main">Roberto Caldeyro-Barcia</span>

Roberto Caldeyro-Barcia was a Uruguayan doctor who pioneered the field of maternal-fetal medicine, or perinatology. His research with Dr. Hermógenes Alvarez created Montevideo units, a measure of uterine performance during labor. He was a founding editor of the Journal of Perinatal Medicine, a widely published author, a lecturer, and as of 2010 the only Uruguayan to be nominated for a Nobel Prize.

Uterine hyperstimulation or hypertonic uterine dysfunction is a potential complication of labor induction. This is displayed as Uterine tachysystole- the contraction frequency numbering more than five in a 10-minute time frame or as contractions exceeding more than two minutes in duration. Uterine hyperstimulation may result in fetal heart rate abnormalities, uterine rupture, or placental abruption. It is usually treated by administering terbutaline.

Amnioinfusion is a method in which isotonic fluid is instilled into the uterine cavity.

Fetal scalp blood testing is a technique used in obstetrics during active labor to confirm whether a fetus is receiving enough oxygen. This is a supplementary procedure used to determine if fetal acidemia has occurred following fetal cardiac distress. While continuous fetal heart rate monitoring is the primary method for assessing fetal wellbeing during labor, a change in fetal heart rate is not indicative of fetal acidemia. Some of the signs and symptoms of oxygen deprivation are pH in the umbilical cord, abnormal fetal heartbeat and abnormal coloration of amniotic fluid. This correlation can only be concluded by sampling fetal scalp blood and measuring acid status. Therefore, fetal scalp blood testing could be used to reduce the number of unnecessary emergency caesarean sections made on the decision of fetal heart rate alone.

Uterine Tachysystole is a condition of excessively frequent uterine contractions during pregnancy. It is most often seen in induced or augmented labor, though it can also occur during spontaneous labor, and this may result in fetal hypoxia and acidosis. This may have serious effects on both the mother and the fetus including hemorrhaging and death. There are still major gaps in understanding treatment as well as clinical outcomes of this condition. Uterine tachysystole is defined as more than 5 contractions in 10 minutes, averaged over a 30-minute period.

Vibroacoustic stimulation (VAS), sometimes referred to as fetal vibroacoustic stimulation or fetal acoustic stimulation test (FAST), is the application of a vibratory sound stimulus to the abdomen of a pregnant woman to induce FHR (fetal heart rate) accelerations. The presence of FHR accelerations reliably predicts the absence of fetal metabolic acidemia. Vibroacoustic stimulation is typically used during a nonstress test (NST).

<span class="mw-page-title-main">Umbilical cord compression</span> Medical condition

Umbilical cord compression is the obstruction of blood flow through the umbilical cord secondary to pressure from an external object or misalignment of the cord itself. Cord compression happens in about one in 10 deliveries.

Fetal scalp stimulation test is a diagnostic test used to detect fetal metabolic acidemia. It can be used as a non-invasive alternative to fetal scalp blood testing.

References

  1. ↑ Kamala, Benjamin A.; Kidanto, Hussen L.; Wangwe, Peter J.; Dalen, Ingvild; Mduma, Estomih R.; Perlman, Jeffrey M.; Ersdal, Hege L. (2018). "Intrapartum fetal heart rate monitoring using a handheld Doppler versus Pinard stethoscope: a randomized controlled study in Dar es Salaam". International Journal of Women's Health. 10: 341–348. doi: 10.2147/IJWH.S160675 . ISSN   1179-1411. PMC   6042559 . PMID   30022861.
  2. ↑ Ayres-de-Campos, Diogo (June 2018). "Electronic fetal monitoring or cardiotocography, 50 years later: what's in a name". American Journal of Obstetrics and Gynecology. 218 (6): 545–546. doi: 10.1016/j.ajog.2018.03.011 . ISSN   0002-9378. PMID   29793572. S2CID   44164963.
  3. ↑ Alfirevic, Zarko; Gyte, Gillian ML; Cuthbert, Anna; Devane, Declan (2017-02-03). Cochrane Pregnancy and Childbirth Group (ed.). "Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour". Cochrane Database of Systematic Reviews. 2019 (5): CD006066. doi:10.1002/14651858.CD006066.pub3. PMC   6464257 . PMID   28157275.
  4. ↑ Kodkin, Vladimir (2022-07-08). "Cardiotocography in Obstetrics: New Solutions for "Routine" Technology". Sensors. 22 (14): 5126. doi: 10.3390/s22145126 . ISSN   1424-8220. PMC   9320740 . PMID   35890806.
  5. ↑ Park, Tae Jun; Chang, Hye Jin; Choi, Byung Jin; Jung, Jung Ah; Kang, Seongwoo; Yoon, Seokyoung; Kim, Miran; Yoon, Dukyong (July 2022). "Machine Learning Model for Classifying the Results of Fetal Cardiotocography Conducted in High-Risk Pregnancies". Yonsei Medical Journal. 63 (7): 692–700. doi: 10.3349/ymj.2022.63.7.692 . ISSN   1976-2437. PMC   9226828 . PMID   35748081.
  6. 1 2 3 Grivell, Rosalie M.; Alfirevic, Zarko; Gyte, Gillian M. L.; Devane, Declan (12 September 2015). "Antenatal cardiotocography for fetal assessment". Cochrane Database of Systematic Reviews . 2019 (9): CD007863. doi: 10.1002/14651858.CD007863.pub4 . PMC   6510058 . PMID   26363287.
  7. 1 2 3 Alfirevic, Zarko; Devane, Declan; Gyte, Gillian M. L.; Cuthbert, Anna (3 February 2017). "Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour". Cochrane Database of Systematic Reviews . 2 (2): CD006066. doi: 10.1002/14651858.CD006066.pub3 . ISSN   1469-493X. PMC   6464257 . PMID   28157275.
  8. 1 2 3 4 5 Callahan, Tamara; Caughey, Aaron B. (January 2013). Blueprints Obstetrics & Gynecology. Baltimore, MD: Lippincott Williams & Wilkins. pp. 43–47. ISBN   978-1-4511-1702-8.
  9. ↑ "Types of Fetal Heart Monitoring". www.hopkinsmedicine.org. Retrieved 21 March 2018.
  10. ↑ "External and Internal Heart Rate Monitoring of the Fetus - Health Encyclopedia - University of Rochester Medical Center". www.urmc.rochester.edu. Retrieved 2022-04-15.
  11. ↑ Nunes, Inês; Ayres-de-Campos, Diogo; Figueiredo, Catarina; Bernardes, João (25 July 2012). "An overview of central fetal monitoring systems in labour". Journal of Perinatal Medicine. 41 (1): 93–99. doi: 10.1515/jpm-2012-0067 . PMID   23093259.
  12. ↑ "Procedures That May Take Place During Labor and Delivery". Penn Medicine. University of Pennsylvania. Archived from the original on 2020-07-27.
  13. ↑ Neilson, James P. (6 February 1993). "Cardiotocography during labour". British Medical Journal . 306 (6874): 347–348. doi: 10.1136/bmj.306.6874.347 . PMC   1676479 . PMID   8461676.
  14. ↑ Al Wattar, Bassel H.; Honess, Emma; Bunnewell, Sarah; Welton, Nicky J.; Quenby, Siobhan; Khan, Khalid S.; Zamora, Javier; Thangaratinam, Shakila (6 April 2021). "Effectiveness of intrapartum fetal surveillance to improve maternal and neonatal outcomes: a systematic review and network meta-analysis". Canadian Medical Association Journal. 193 (14): E468–E477. doi: 10.1503/cmaj.202538 . PMC   8049638 . PMID   33824144.
  15. 1 2 3 4 5 6 7 8 9 10 Macones, George A.; Hankins, Gary D. V.; Spong, Catherine Y.; Hauth, John; Moore, Thomas (2008). "The 2008 National Institute of Child Health and Human Development Workshop Report on Electronic Fetal Monitoring". Obstetrics & Gynecology . 112 (3): 661–666. doi:10.1097/AOG.0b013e3181841395. PMID   18757666. S2CID   1884812.
  16. ↑ "NICE Guideline Intrapartum care: management and delivery of care to women in labour". Archived from the original on 2011-07-27.
  17. ↑ "Fetal Health Surveillance: Antepartum and Intrapartum Consensus Guideline" (PDF). Journal of Obstetrics and Gynaecology Canada. 29 (9). September 2007. Archived from the original (PDF) on 2010-11-29.
  18. ↑ "How to Read a CTG | CTG Interpretation". May 11, 2021. Retrieved 2021-06-05.
  19. ↑ Pani, Danilo; Rabotti, Chiara; Signorini, Maria Gabriella; Burattini, Laura (2020-10-20). Innovative Technologies and Signal Processing in Perinatal Medicine: Volume 1. Springer Nature. ISBN   978-3-030-54403-4.
  20. 1 2 3 4 5 Tarvonen, Mikko; Hovi, Petteri; Sainio, Susanna; Vuorela, Piia; Andersson, Sture; Teramo, Kari (2020-09-27). "Intrapartum zigzag pattern of fetal heart rate is an early sign of fetal hypoxia: A large obstetric retrospective cohort study". Acta Obstetricia et Gynecologica Scandinavica . 100 (2): 252–262. doi: 10.1111/aogs.14007 . ISSN   0001-6349. PMC   7894352 . PMID   32981037.
  21. 1 2 3 Tarvonen, Mikko; Sainio, Susanna; Hämäläinen, Esa; Hiilesmaa, Vilho; Andersson, Sture; Teramo, Kari (2019-12-17). "Saltatory Pattern of Fetal Heart Rate during Labor Is a Sign of Fetal Hypoxia". Neonatology. 117 (1): 111–117. doi:10.1159/000504941. ISSN   1661-7819. PMID   31846958. S2CID   209408174.
  22. 1 2 Gracia-Perez-Bonfils, Anna; Cuadras, Daniel; Whelehan, Virginia; Archer, Abigail; Del Río, Maria; Chandraharan, Edwin (March 2019). "Saltatory pattern vs Zigzag pattern on the CTG, and perinatal outcomes". European Journal of Obstetrics & Gynecology and Reproductive Biology . 234: e55. doi:10.1016/j.ejogrb.2018.08.276. ISSN   0301-2115. S2CID   86491442.
  23. ↑ Polnaszek, Brock; López, Julia D.; Clark, Reece; Raghuraman, Nandini; Macones, George A.; Cahill, Alison G. (2019-10-02). "Marked variability in intrapartum electronic fetal heart rate patterns: association with neonatal morbidity and abnormal arterial cord gas". Journal of Perinatology . 40 (1): 56–62. doi:10.1038/s41372-019-0520-9. ISSN   0743-8346. PMC   7202403 . PMID   31578422.
  24. ↑ Tarvonen, Mikko (2021). "Factors Associated with Intrapartum ZigZag Pattern of Fetal Heart Rate: A Retrospective One-Year Cohort Study of 5150 Singleton Childbirths". European Journal of Obstetrics, Gynecology, and Reproductive Biology. 258: 118–125. doi:10.1016/j.ejogrb.2020.12.056. PMID   33421808. S2CID   231437287.
  25. 1 2 Norwitz, Errol R.; Zelop, Carolyn M.; Miller, David A.; Keefe, David L. (2018-12-20). Evidence-based Obstetrics and Gynecology. John Wiley & Sons. ISBN   978-1-119-07295-9.
  26. 1 2 3 4 Ayres-de-Campos, Diogo; Spong, Catherine Y; Chandraharan, Edwin (October 2015). "FIGO consensus guidelines on intrapartum fetal monitoring: Cardiotocography". International Journal of Gynecology & Obstetrics . 131 (1): 13–24. doi: 10.1016/j.ijgo.2015.06.020 . hdl: 10067/1401570151162165141 . ISSN   1879-3479. PMID   26433401.
  27. ↑ Tarvonen, Mikko; Hovi, Petteri; Sainio, Susanna; Vuorela, Piia; Andersson, Sture; Teramo, Kari (2021-06-21). "Intrapartal cardiotocographic patterns and hypoxia-related perinatal outcomes in pregnancies complicated by gestational diabetes mellitus". Acta Diabetologica. 58 (11): 1563–1573. doi: 10.1007/s00592-021-01756-0 . ISSN   1432-5233. PMC   8505288 . PMID   34151398.
  28. 1 2 "NICE/RCOG CTG Guidelines 2017" (PDF). National Institute for Health and Care Excellence . 3 December 2014. Archived from the original on 2020-07-27.
  29. ↑ O'Brien-Abel, Nancy E.; Benedetti, Thomas J. (March 1992). "Saltatory Fetal Heart Rate Pattern". Journal of Perinatology . 12 (1): 13–17. ISSN   0743-8346. PMID   1560284.
  30. ↑ Yanamandra, Niraj; Chandraharan, Edwin (2013-07-31). "Saltatory and Sinusoidal Fetal Heart Rate (FHR) Patterns and significance of FHR 'Overshoots'". Current Women's Health Reviews. 9 (3): 175–182. doi:10.2174/157340480903140131111914.
  31. ↑ Nunes, I.; Ayres-de-Campos, D.; Kwee, A.; Rosén, K. G. (2014). "Prolonged saltatory fetal heart rate pattern leading to newborn metabolic acidosis". Clinical and Experimental Obstetrics & Gynecology. 41 (5): 507–511. doi: 10.12891/ceog17322014 . ISSN   0390-6663. PMID   25864248. S2CID   42931226.
  32. ↑ Tarvonen, Mikko; Sainio, Susanna; Hämäläinen, Esa; Hiilesmaa, Vilho; Andersson, Sture; Teramo, Kari (February 19, 2020). "Saltatory Pattern of Fetal Heart Rate during Labor Is a Sign of Fetal Hypoxia". Neonatology. 117 (1): 111–117. doi:10.1159/000504941. PMID   31846958. S2CID   209408174 – via www.karger.com.
  33. ↑ Tarvonen, MJ; Lear, CA; Andersson, S; Gunn, AJ; Teramo, KA (2022). "Increased variability of fetal heart rate during labour: a review of preclinical and clinical studies". BJOG. 2022 (12): 2070–2081. doi: 10.1111/1471-0528.17234 . PMC   9796294 . PMID   35596699. S2CID   248948040.
  34. ↑ Tarvonen, Mikko (13 March 2023). "Increased variability of fetal heart rate: from evidence to implementation". BJOG. 2023, 00:1–2 (12): 1558–1559. doi:10.1111/1471-0528.17488. PMID   37055662. S2CID   258135555 – via PubMed.
  35. ↑ Bailey, R. Eugene (15 December 2009). "Intrapartum Fetal Monitoring". American Family Physician . 80 (12): 1388–1396. PMID   20000301.
  36. ↑ "Available to view: FIGO Intrapartum Fetal Monitoring Guidelines". International Federation of Gynecology and Obstetrics (FIGO). Retrieved 2017-06-26.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.