Miscarriage

Overview

Miscarriage is the spontaneous end of a pregnancy before 24 weeks' gestation (the older term "spontaneous abortion" is still used in Pakistan and in exam papers). It is very common: 10-20% of clinically recognised pregnancies miscarry, and the risk rises with maternal age. Most occur in the first trimester.

Two jobs in every case: (1) make sure she is safe (bleeding, shock, infection, ectopic excluded) and (2) name the type, because the type decides management. Remember the emotional side: many women feel grief and guilt and need to hear that most miscarriages are one-off events and not their fault.

Early pregnancy basics for the exam

• Implantation occurs about 7 days after ovulation; the blastocyst makes hCG, which keeps the corpus luteum producing progesterone for about 8 weeks, after which the placenta takes over (luteo-placental shift).
• On transvaginal scan: gestational sac at about 5 weeks, yolk sac a few days later, fetal pole after about 5.5 weeks, heartbeat from about 6 weeks.
• In a normal early pregnancy serum hCG roughly doubles every 48 hours; above about 1,500 IU/L an intrauterine pregnancy should be visible on TVUSS.
• A biochemical pregnancy is a positive test followed by a period: very early loss at implantation.

Causes

Types of miscarriage

Assessment

• ABCDE: pulse, blood pressure, perfusion. Heavy bleeding can cause hypovolaemic shock.
• Cervical shock: products of conception stuck in the cervical os stimulate the vagus and cause bradycardia and hypotension out of proportion to blood loss. Remove the tissue with sponge forceps at speculum examination; the pulse and blood pressure recover quickly.
• Speculum: amount of bleeding, os open or closed, tissue in the os, other causes (cervical lesion).
• Transvaginal ultrasound: location and viability.
• Haemoglobin and group and save (cross-match if compromised): to assess loss and Rhesus status.
• Serum hCG if the site of the pregnancy is unknown.

Ultrasound criteria for missed miscarriage

A single TVUSS can diagnose miscarriage when:

• Crown-rump length (CRL) is 7 mm or more with no heartbeat, or
• Mean gestational sac diameter is over 25 mm with no fetal pole.

In both cases get a second opinion and/or repeat the scan at least 7 days later before acting, so that a viable pregnancy is never ended by mistake.

Management of miscarriage

Expectant (natural)

• First-line for 7-14 days after diagnosis for most women.
• Avoids surgery; no routine scan needed if pain and bleeding settle; a urine pregnancy test after 3 weeks.
• Not suitable if: infection, high risk of haemorrhage (late first trimester, bleeding disorder, previous severe haemorrhage), she declines blood transfusion, or previous traumatic pregnancy experience.

Medical

• Misoprostol (prostaglandin E1 analogue), vaginal or oral, single or repeated doses; sometimes after mifepristone (progesterone receptor blocker) pre-treatment. Often done at home.
• Side effects: pain, vomiting, diarrhoea: give analgesia and antiemetics.
• About 10% fail and need surgery; a pregnancy test afterwards confirms completion.

Surgical

• Indicated for heavy or persistent bleeding, haemodynamic instability, infected retained tissue, failed medical or expectant treatment, or the woman's choice.
• Manual vacuum aspiration under local anaesthesia (outpatient), or suction evacuation under general anaesthesia (day case).
• Cervical priming with misoprostol (or osmotic dilators) reduces cervical injury; Ten Teachers gives 400 micrograms sublingually 1 hour before surgical evacuation.
• Complications: uterine perforation (with possible bowel or bladder injury), bleeding, infection, cervical trauma, retained tissue, intrauterine adhesions (Asherman syndrome).
• Sharp curettage of the soft pregnant uterus damages the basal endometrium and is avoided.

Septic miscarriage

• Usually follows retained products or unsafe induced abortion (commonest setting in low-resource countries).
• Fever, tachycardia, foul-smelling discharge, tender uterus; may progress to sepsis, peritonitis, renal failure and DIC.
• Resuscitate, blood cultures, IV broad-spectrum antibiotics, then evacuate the uterus promptly; look for perforation and bowel injury after instrumentation.

Anti-D in early pregnancy

• Give anti-D immunoglobulin 250 IU (50 micrograms) within 72 hours to all Rh-negative women who have surgical management of a miscarriage (or ectopic).
• Not needed for threatened, incomplete or complete natural miscarriage in the first trimester (local guidance varies); often given after medical management.
• Kleihauer test is not needed in the first trimester.

Recurrent miscarriage

• Three or more consecutive pregnancy losses; affects about 1% of couples.
• Risk factors: older maternal (and paternal) age, obesity, antiphospholipid syndrome (APS), balanced parental chromosomal translocation, uterine anomalies (septum), cervical weakness, poorly controlled diabetes or thyroid disease.
• Investigations:
  • Antiphospholipid antibodies: lupus anticoagulant and anticardiolipin (repeat to confirm).
  • Pelvic ultrasound (3D if possible) for uterine anomalies.
  • Karyotype of pregnancy tissue from the next loss; parental karyotyping if it shows an unbalanced structural abnormality.
• Treatment:
  • APS: low-dose aspirin + heparin in pregnancy reduces the miscarriage rate by about half.
  • Balanced translocation: genetic counselling; pre-implantation genetic diagnosis or donor gametes.
  • Uterine septum and cervical weakness: may be helped by surgery.
  • Progesterone may help women with recurrent miscarriage who now have bleeding (threatened miscarriage); steroids and metformin are not recommended routinely.
• Most couples have normal tests and a good chance of success with supportive care and early scans.

Second-trimester loss and cervical weakness

• Cervical weakness (incompetence): painless cervical dilatation in the second trimester, with bulging membranes and rapid, near-painless delivery.
• Risk factors: previous cervical surgery (cone biopsy, repeated LLETZ), repeated cervical dilatation, previous mid-trimester loss.
• Cervical cerclage (a stitch around the cervix):
  • History-indicated: after repeated mid-trimester losses or preterm births.
  • Ultrasound-indicated: if the cervix shortens (usually under 25 mm) in a woman with risk factors.
  • Rescue: cervix already dilating without contractions.
  • Types: McDonald (transvaginal purse-string), Shirodkar (placed higher, after pushing the bladder up), transabdominal (after a failed vaginal stitch or extensive cervical surgery).
• Cerclage does not help in multiple pregnancy.

Quick revision

• Miscarriage: loss before 24 weeks; 10-20% of clinical pregnancies; bleeding is the main sign.
• First trimester: chromosomes (50-70%); second trimester: cervix or uterus.
• Threatened: os closed, live. Inevitable: os open. Incomplete: tissue in os. Complete: empty, closed. Missed: no heart, no symptoms.
• Diagnose missed miscarriage: CRL 7 mm or more without heartbeat, or sac over 25 mm without pole; confirm.
• Options: expectant (first-line 7-14 days), misoprostol, vacuum aspiration.
• Anti-D 250 IU within 72 hours for Rh-negative after surgery.
• Recurrent: 3 or more, 1% of couples; test APS, uterine shape, karyotype; aspirin + heparin for APS.
• Cervical weakness: painless mid-trimester loss; cerclage.

Written by The House Job from standard references (Gynaecology by Ten Teachers; Obstetrics by Ten Teachers).

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