Chapter 15 Early Pregnancy
Miscarriage
Miscarriage occurs in 10–20% of clinical pregnancies, and in the UK it is defined as a pregnancy loss before the 24th week of gestation. In Australia, miscarriage is a pregnancy that spontaneously ends before 20 weeks. After the 20th week of pregnancy, the loss of a fetus is called a stillbirth.
Threatened miscarriage
Technically this refers only to bleeding from the placental site, which is not yet severe enough to terminate the pregnancy. Usually the bleeding is slight and the cervix remains closed. The pregnancy is likely to remain viable.
Inevitable miscarriage
Clinically, the amount of bleeding is variable but the cervix is open. On ultrasound examination, the bleeding is retroplacental and often, fetal heart activity is absent.
Complete miscarriage
A miscarriage in which the fetus, membranes and chorionic tissue are completely expelled from the uterus is termed a complete miscarriage.
Incomplete miscarriage
A miscarriage in which the fetus or membranes or chorionic tissue are incompletely expelled from the uterus. An ultrasound will show debris (retained products of conception) within the uterine cavity.
Missed miscarriage
It is defined as the retention of a non-viable fetus for several weeks without any clinical symptoms.
Management
The method of management of miscarriage depends upon the gestation of miscarriage and clinical facilities available. Apart from expectant management, these methods are identical to those performed during an elective termination of pregnancy.
Early pregnancy loss (≤12Weeks’ Gestation)
Surgical
Clinical indications for surgical evacuation include: persistent excessive bleeding, haemodynamic instability, evidence of infected retained tissue, suspected gestational trophoblastic disease and patient choice. Surgical uterine evacuation for a miscarriage should be performed using a suction curettage. Where infection is suspected, delaying surgical intervention for 12 h is recommended to allow intravenous antibiotic administration.
Preoperative cervical preparation essentially softens the cervix making it easier to dilate and, in doing so, minimises force of dilatation required, haemorrhage and uterine/cervical trauma. The cervix can be prepared using:
Surgical Evacuation of the Products of Conception
Curettage
The patient is anaesthetised and the cervix is dilated. Once dilatation is sufficient, vacuum aspiration of the uterine contents is carried out.
A plastic suction curette is commonly used and is less likely to damage the uterus than metal instruments. Plastic curettes are available in diameters from 4 to 12 mm. The cervix is conventionally dilated to a diameter that is 2 mm less than the gestation age in weeks.
Complications
Further tissue can be removed with a sponge forcep or a curette. The concave side of the curette loop is pressed against the uterine wall and pulled down. A ‘clean’ uterine wall gives a characteristic sensation to the operating hand.
Reported serious complications of surgery include perforation of the uterus, cervical tears, intra-abdominal trauma, intrauterine adhesions and haemorrhage.
Medical
Medical methods are an effective alternative in the management of a confirmed first-trimester miscarriage. Various medical methods have been described which use prostaglandin analogues (gemeprost or misoprostol) with or without antiprogesterone priming (mifepristone). Protocols should be developed locally with appropriate selection criteria, therapeutic regimens and arrangements for follow-up. To avoid unnecessary anxiety, women should be informed that bleeding may continue for up to 3 weeks after medical uterine evacuation.
Expectant
Expectant management is a method that can be offered in cases of confirmed first trimester miscarriage. Patient counselling is particularly important for those women with an intact sac who wish to adopt an expectant approach. They should be aware that complete resolution may take several weeks. Expectant management for incomplete miscarriage is highly effective. Occasionally, the passage of tissue may be associated with heavy bleeding.
Medical and expectant management should only be offered in units where women have access to 24-h telephone advice and emergency admission, if required.
Anti-D Immunoglobulin
Non-sensitised rhesus (Rh) negative women should receive anti-D immunoglobulin in the following situations: ectopic pregnancy, all miscarriages over 12 weeks of gestation (including threatened) and all miscarriages where the uterus has been evacuated (whether medially or surgically).
Anti-D immunoglobulin is not required threatened miscarriages under 12 weeks of gestation unless the bleeding is heavy or is associated with significant pain. It is not required in cases of complete miscarriage under 12 weeks’ gestation and when there has been no formal intervention to evacuate the uterus.
Late pregnancy loss (>12Weeks’ Gestation)
Surgical
Surgical uterine evacuation remains an option for some women. Dilatation and suction curettage is commonly performed up to 14 weeks’ gestation. Beyond this point, dilatation and evacuation (D & E) can be carried out which involves cervical dilatation to a maximum diameter and the removal of intrauterine contents, usually following a destructive procedure. This procedure is not commonly performed in the UK.
Medical
Again, medical methods are effective in the management of a second trimester miscarriage. As in the case of first trimester loss, there are various medical regimens that have been described using prostaglandin analogues (gemeprost or misoprostol) with or without antiprogesterone priming (mifepristone). Again, local protocols should be developed appropriately with selection criteria, therapeutic regimens and arrangements for follow-up.
In cases where antiprogesterones and vaginal prostaglandins are not available, PGE2 can be very slowly instilled into the cervix through a Foley catheter to facilitate cervical ripening.
Recurrent miscarriage
Introduction and definitions
Recurrent miscarriage, defined as the loss of three or more pregnancies, is a distressing problem that affects up to 1% of women. Recurrent miscarriage is a heterogeneous condition that has many possible causes; more than one contributory factor may underlie the recurrent pregnancy losses.
Causes of recurrent miscarriage
Maternal Age
This is an independent risk factor. Advanced maternal age adversely affects ovarian function, giving rise to a decline in the number of good quality oocytes and resulting in chromosomally abnormal conceptions that rarely develop further.
Previous Number of Miscarriages
This is an independent risk factor in so far as the more miscarriages an individual has had, the more likely she is to have another one.
Genetic Factors
In approximately 3–5% of couples with recurrent miscarriage, one of the partners carries a balanced structural chromosomal anomaly. These are most commonly balanced reciprocal or Robertsonian translocations.
Abnormalities in the Embryo
Recurrent pregnancy loss may be owing to an abnormal embryo which is incompatible with life. As the number of miscarriages increases, the presence of a chromosomal abnormality decreases and the chance of a recurring maternal cause increases.
Uterine Abnormalities
It is difficult to assess the exact contribution that congenital uterine anomalies make to recurrent miscarriage. The estimates of the number of women with recurrent miscarriage, who also have uterine abnormalities, range from 2% to 37%. Women who have serious anatomical abnormalities and have not had treatment for them seem to be more likely to miscarry or give birth early. Minor variations in the structure of the womb generally do not cause miscarriage
Cervical Weakness
The diagnosis of cervical weakness (previously known as incompetence) is usually based on a history of late miscarriage, preceded by spontaneous rupture of membranes or a painless cervical dilatation. This is often over diagnosed as there is currently no satisfactory, objective test that can identify women with cervical weakness in the non-pregnant state.
Full access? Get Clinical Tree
