Fetoscopy is a procedure that utilizes an instrument called a fetoscope to evaluate or treat the fetus during pregnancy.
There are two different types of fetoscopy: external and endoscopic.
An external fetoscope resembles a stethoscope , but with a headpiece. It is used externally on the mother's abdomen to auscultate (listen to) the fetal heart tones after about 18 weeks gestation. It also allows a birth attendant to monitor the fetus intermittently and ensure that the baby is tolerating labor without the mother having to be attached to a continuous fetal monitor.
The second type of fetoscope is a fiber-optic endoscope. It is inserted into the uterus either transabdominally (through the abdomen) or transcervically (through the cervix) to visualize the fetus, to obtain fetal tissue samples, or to perform fetal surgery .
Approximately 3% of babies born in the United States each year have a complex birth defect. Certain birth defects are complicated by the labor and delivery process, while others may progress quickly after birth to cause significant disability or death. Fetal surgical techniques utilizing the endoscopic fetoscope offer early intervention in order to treat such defects before they become serious.
Some of the fetal abnormalities that may be treated by endoscopic fetoscopy are:
- Congenital diaphragmatic hernia (CDH). In babies with CDH, the diaphragm (the thin muscle that separates the chest from the abdomen) doesn't develop properly. The abdominal organs may enter the chest cavity through a hole (hernia) and cause pulmonary hyperplasia (underdeveloped lungs). CDH occurs in about one out of every 2,000 births.
- Urinary tract obstruction. The urethra (the tube that carries urine from the bladder to the outside of the body) may become obstructed in utero or fail to develop normally. When this happens, urine can back up into the kidneys and destroy tissue or cause the bladder to become enlarged. The amount of amniotic fluid also decreases because fetal urine is its major component. Pulmonary hypoplasia usually results because the lungs rely on amniotic fluid in their development.
- Twin/twin transfusion syndrome (TTTS). In some twin pregnancies, the two fetuses will share a placenta (called a monochorionic pregnancy). TTTS occurs in approximately 15% of these twins when blood volume between the fetuses is unequal, causing abnormally low blood volume in the donor twin and abnormally high blood volume in the recipient twin. There is often a large difference in size between the twins. Approximately 70–80% of fetuses suffering from TTTS will die without intervention.
- Acardiac twin. This condition also occurs in monochorionic pregnancies, but one twin develops normally while the other develops without a heart. The acardiac twin receives its blood supply from the normal twin, whose heart must now work harder to pump blood through both fetuses. Approximately 50–75% of acardiac twins will die as a result. An acardiac twin occurs in 1% of monochorionic pregnancies and one out of 35,000 overall pregnancies.
External fetoscopy may be used to determine the fetal heart rate in any woman with a viable pregnancy, although certain circumstances may compromise its quality (a noisy environment, an obese mother, or hydramnios [excess amniotic fluid]).
No demographic data are available regarding patients undergoing operative fetoscopy, since it is a relatively new procedure being performed at only a handful of hospitals around the United States.
The external fetoscope is used to listen to fetal heart tones for rate and rhythm. The earpieces and the headpiece allow auscultation (listening) via both air and bone conduction. External fetoscopy is inexpensive, noninvasive, and does not require electricity. It is difficult, however, to clearly hear the fetal heart tones prior to 18 to 20 weeks gestation. Doppler ultrasound can detect fetal heart tones around weeks 10 to 12.
Endoscopic fetoscopy uses a thin (1 mm) fiberoptic scope. Developed in the 1970s, the endoscope was originally inserted transabdominally to visualize the fetus for gross abnormalities suspected by ultrasound or to obtain tissue and blood samples. It was performed after about 18 weeks gestation. Even with practitioner expertise, associated fetal loss was 3–7%. During the 1980s, ultra-sound-guided needle sampling of cord blood replaced fetoscopy when samples of fetal blood were required.
As laparoscopic and microsurgical techniques have become more common and the instrumentation has become more advanced technologically, fetoscopy has improved for fetal diagnostic and therapeutic purposes. Fetal surgery performed through an open maternal abdomen has a higher risk of such complications as infection, premature rupture of membranes, preterm labor, or fetal death. If surgery is performed via fetoscopy, which requires a very small transabdominal incision, the risks are much smaller. Techniques have advanced enough to allow some fetoscopy to be performed in the first trimester via the mother's cervix. The term "obstetrical endoscopy" may be used for surgery on the placenta, umbilical cord, or on the fetal membranes. The term "endoscopic fetal surgery" is used for such procedures as the repair of a fetal congenital diaphragmatic hernia or obstructed bladder.
The use of external fetoscopy requires access to the maternal abdomen, with the mother lying supine or in a semi-seated position. Afterwards, the mother is able to get up and resume a normal activity level.
Preparation for endoscopic fetoscopy will depend on the extent of the procedure, and whether it is performed transcervically or transabdominally. Obtaining a small fetal tissue sample is a smaller procedure by comparison to fetal surgery. Other factors include outpatient versus inpatient stay and anesthesia (both maternal and fetal). For some procedures medication may be administered to temporarily decrease fetal movement to lower the risk of fetal injury. Maternal anesthesia may be local, regional, or general.
External fetoscopy does not require aftercare. The care following fetal endoscopic use will depend on the extent of the procedure and the type of anesthesia used. If the procedure is done on an outpatient basis, the mother and fetus will be monitored for a period of time prior to discharge. More extensive surgery will require inpatient hospital postoperative care .
The only potential complication with external fetoscopy is the possibility of missing an abnormal heart rate or rhythm. Its usefulness and accuracy depend on the skill of the practitioner.
Endoscopic fetoscopy has the potential for causing infection in the fetus and/or mother; premature rupture of the amniotic membranes; premature labor; and fetal death. When endoscopic fetal surgery is done instead of open-uterus fetal surgery, the risks to the mother and fetus are decreased. The risks are because the incision is significantly smaller, with less potential blood loss, decreased uterine irritability, and decreased risk of early miscarriage.
The normal fetal heart rate is 120 to 160 beats per minute, regardless of the method used for auscultation (external fetoscopy or Doppler ultrasound). Some variability of fetal heart rate is expected, as the heart rate increases with fetal activity and slows with fetal rest.
Results expected using endoscopic fetoscopy will vary depending on the procedure undertaken. The goal is for the maximum benefit with the minimum of risk or complication to both the mother and fetus.
Morbidity and mortality rates
There is no morbidity or mortality associated with external fetoscopy. In the case of endoscopic fetoscopy, the risk of fetal loss is estimated to be between 3% and 5%. The procedure is therefore usually recommended only for the more severe cases of fetal disorders that may be treated during pregnancy.
A health care provider may listen to the fetal heart rate by means of a hand-held Doppler device, which uses ultrasound to amplify the heart beat. A continuous electronic fetal monitor may also be used to track the fetal heart rate and maternal uterine contractions. It is held against the mother's abdomen by means of elastic straps.
Open fetal surgery is an alternative to internal fetoscopy. It is used for conditions that cannot be treated endoscopically. An incision is made through the abdomen and the uterus is partially removed from the body. Amniotic fluid is drained from the uterus and kept in a warmer for replacement after completion of the surgery. An incision is made in the uterus (called a hysterotomy). In order to minimize bleeding of the uterus, an instrument called a uterine stapler is used to make an incision while simultaneously placing staples around the perimeter of the incision to prevent bleeding. Surgery is then performed on the fetus through the opening in the uterus to locate the abnormality and remove or repair it. There is a greater risk of infection, premature labor, and leakage of amniotic fluid with open fetal surgery than there is with fetoscopy.
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Esther Csapo Rastegari, R.N., B.S.N., Ed.M.
Stephanie Dionne Sherk
WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?
Health-care profesionals who may use the external fetoscope include a nurse practitioner, nurse midwife, and obstetrician. External fetoscopy may be performed in any setting with the pregnant woman lying supine or in a semi-sitting position. Endoscopic fetoscopy requires a high level of skill and experience by fetal surgeons and is performed in a hospital setting. During the procedures, a radiology technician may perform an ultrasound, and a laboratory technician may be involved in blood sampling. Nurses will participate in both outpatient and inpatient procedures.
QUESTIONS TO ASK THE DOCTOR
- Why is fetoscopy recommended in my case?
- What alternatives to fetoscopy are available to me?
- For endoscopic fetoscopy, what will be the results if there is no medical intervention?
- For endoscopic fetoscopy, will the procedure be performed on an outpatient basis? What type of anesthesia will be used?
"Fetoscopy." Gale Encyclopedia of Surgery: A Guide for Patients and Caregivers. . Encyclopedia.com. (August 22, 2017). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/fetoscopy
"Fetoscopy." Gale Encyclopedia of Surgery: A Guide for Patients and Caregivers. . Retrieved August 22, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/fetoscopy
"fetoscopy." A Dictionary of Nursing. . Encyclopedia.com. (August 22, 2017). http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/fetoscopy
"fetoscopy." A Dictionary of Nursing. . Retrieved August 22, 2017 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/fetoscopy