There are two different types of fetoscopes. One resembles a stethoscope, but with a headpiece. It is used externally, on the mother's abdomen, to auscultate (listen to) the fetal heart tones. The second type of fetoscope is a fiber-optic endoscope. It is inserted into the uterus either transabdominally or transcervically to visualize the fetus, to obtain fetal tissue samples, or to perform fetal surgery.
The external fetoscope requires no preparation, nor does it have any associated risks. Its usefulness and accuracy depend on the skill of the practitioner. The endoscopic fetoscope is inserted internally and thus carries risks of infection (both maternal and fetal), premature rupture of membranes, premature labor, and fetal death. The American College of Obstetricians and Gynecologists expressed their opinion in a February 28, 2001 press release that fetal surgery should be considered experimental.
The external fetoscope is used to auscultate fetal heart tones for rate and rhythm. The earpieces and the headpiece allow auscultation via both air and bone conduction. It is inexpensive, is not invasive, and does not require electricity. It is difficult to clearly hear the fetal heart tones prior to 18 to 20 weeks gestation. Doppler ultrasound can measure fetal heart tones around weeks 10 to 12. External fetoscopy is compromised in a noisy environment, with an obese mother due to the large abdomen, and in the case of hydramnios.
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 three to seven percent. In the 1980s ultrasound-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, the expertise gained has carried over to fetoscopy, improving its use 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 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, enlarged bladder, and spina bifida.
Auscultation—Auscultation uses the sense of hearing to evaluate such internal organs as the heart or bowel. While the practitioner may simply use his or her ears directly, most commonly auscultation is performed with an instrument, such as a fetoscope or stethoscope.
Hydramnios—Hydramnios is the excessive production of amniotic fluid due to either fetal or maternal conditions.
Supine—Lying horizontally on one's back.
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 done on an outpatient basis, the mother and fetus will be monitored for a period of time to assure well-being before discharge. More extensive surgery will require inpatient hospital care.
The only potential complication with external fetoscopy is the potential for missing an abnormal heart rate or rhythm. Endoscopic fetoscopy has the potential for infection to 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. This is because the incision is significantly smaller, with less potential blood loss, decreased uterine irritability, and decreased risk for early pregnancy termination.
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.
Health care team roles
Individuals utilizing the external fetoscope include a nurse practitioner, nurse midwife, and obstetrician. For endoscopic fetoscopy, the procedures require a high level of skill and experience by fetal surgeons. 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 as well as inpatient procedures.
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American College of Obstetricians and Gynecologists. 409 12th St., S.W., PO Box 96920. Washington, D.C. 20090–6920. <http://www.acog.com>.
Florida Institute for Fetal Diagnosis and Therapy. 13601 Bruce B. Downs Boulevard, Suite 160. Tampa, FL33613. Phone: 888-FETAL-77, (888–338–2577). Fax:(813) 872–3794. <http://www.fetalmd.com>.
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Esther Csapo Rastegari, R.N., B.S.N., Ed.M