sponta abortion

Introduction

  • Abortion refers to the spontaneous discharge of the gestation sac before the fetus is viable.

    • Previously applied to fetal loss up to 28 weeks of gestation; since October 1992, it applies to losses up to 24 weeks.

    • Commonly referred to as miscarriage by the lay public.

  • Occurs in approximately 50% of pregnancies; about 15% are clinically recognized.

    • The majority occurs within the first 14 days following conception.

  • Increasing maternal age correlates with elevated fetal loss.

Aetiology of Spontaneous Abortion

Spontaneous abortions are classified based on various aetiological factors:

  1. Maternal Factors

    • General Factors

    • Responsible for about 10% of cases; include maternal illnesses such as pyrexia.

    • Chromosomal abnormalities can cause miscarriage, particularly in recurrent cases (5-10% of couples).

    • Hypertension increases abortion risk; controlling blood pressure may reduce risks.

    • Other factors include systemic lupus erythematosus, thyroid dysfunction, infections (e.g., TORCH), smoking, and alcohol use.

    • Local Factors

    • Cervical incompetence and uterine abnormalities.

    • Higher maternal age is associated with increased risk of abortion.

  2. Foetal Factors

    • Chromosomal abnormalities account for about 60% of early spontaneous abortions (0-7 weeks).

    • Structural abnormalities, such as anencephaly, account for about 20% of cases.

  3. Paternal Factors

    • Chromosomal translocations in fathers may create abnormal gametes, leading to spontaneous abortions.

    • Approximately 1 in 10 couples with recurrent abortions may have a partner with chromosomal abnormalities.

    • Immunological factors may play a role; lack of maternal blocking antibodies in response to paternal antigens is associated with recurrent abortion.

Cervical Incompetence

Description

  • Cervical incompetence is when the cervix is prone to dilate abnormally in the second trimester, leading to spontaneous abortion.

  • Usually painless evacuation occurs without bleeding; uterine contractions are infrequent.

Aetiology

  • Congenital in approximately 30% (related to congenital fundal abnormalities).

  • Generally acquired, often due to trauma, such as:

    • Lateral cervical tears during delivery,

    • Cone biopsy procedures,

    • Surgical dilation for termination of pregnancy.

  • May also result from hormonal activity affecting cervical relaxation, high collagenolytic activity, or low collagen-muscle ratio.

Diagnosis

  • History and vaginal examination are key for diagnosis.

  • Useful investigations include:

    • Hysterography (radiography post-contrast), showing funnelling of the endocervical canal.

    • Retrograde dilatation evaluation (easy insertion of Hegar dilators).

    • Ultrasound scans; check internal os diameter and endocervical canal length.

Management

  • Corrective measures include cervical encerclage, involving placing a suture around the supravaginal cervix at the internal os level.

    • Commonly done via transvaginal approach (Shirodkar or McDonald suture).

    • Best inserted between 14-16 weeks gestation, removed at 38 weeks or earlier if necessary.

  • Suture failure to remove may cause cervical tears or uterine rupture.

  • A transabdominal approach is required for congenitally malformed cervices, usually requiring C-section for delivery.

Epidemiology

  • Approximately 50% of all conceptions may abort spontaneously; 35% are biochemical pregnancies, often undetected.

  • Most clinically recognized cases abort within the first 14 days following conception.

  • The average fetal loss rate between 8-28 weeks is around 3%.

Influence Factors on Spontaneous Abortion

  • Maternal Age:

    • Fetal loss rates increase from <2% in women <30 years to 5-10% for those >40.

  • Parity:

    • Increased risk correlates with higher parity independently of maternal age.

  • Pregnancy Spacing:

    • Optimal intervals between pregnancies are 12-36 months; shorter or longer intervals slightly increase abortion risks.

  • Previous Fetal Losses:

    • A history of previous miscarriages raises relative risk for subsequent losses.

  • Prostaglandin termination may lead to complications like uterine synechiae or cervical incompetence.

  • Smoking and other toxic exposures also elevate abortion incidence.

Chromosomal Abnormalities as Causes of Abortion

  • Early abortions are frequently caused by chromosomal abnormalities:

    • 60% in the 0-7 weeks range,

    • 23% in the 8-12 weeks range.

  • While chromosomal abnormalities are related to spontaneous abortion in later trimesters, their relative importance diminishes compared to other factors.

Types of Abortion

  1. Threatened Abortion

    • Characterized by vaginal bleeding with closed cervix, uterus normal size for dates, absence of products of conception.

  2. Inevitable Abortion

    • Considerable bleeding, lower abdominal pain, dilated cervix, and possible passage of products. Possible outcomes include complete or incomplete abortion.

  3. Incomplete Abortion

    • Products of conception remain. Treatment may involve evacuation due to significant blood loss or ongoing haemorrhage.

  4. Complete Abortion

    • All products expelled; bleeding typically ceases after, and no intervention may be necessary.

  5. Missed Abortion

    • Fetal death occurs yet remains in utero. Diagnosis requires absence of fetal heart sounds or movements and may necessitate evacuation.

  6. Recurrent Abortion

    • Defined as three or more consecutive spontaneous abortions, commonly linked to previous miscarriages.

Aetiology of Recurrent Abortion

  • Possible causes include:

    • Chromosomal abnormalities in either partner

    • Uterine abnormalities

    • Serious chronic diseases (e.g., syphilis, renal disease)

    • Antiphospholipid syndrome present in about 20% of recurrent cases

    • Other factors such as cervical incompetence and polycystic ovarian syndrome (PCOS).

    • Smoking and idiopathic causes contribute to recurrent losses.

Investigations for Recurrent Abortion

  • Comprehensive testing, including:

    • Full blood count (FBC), mid-stream urine (MSU), serological tests, chromosome analysis, screening for hypercoagulable states, and ultrasound imaging.

Treatment for Recurrent Abortion

  • Management should focus on identifying contributing factors and providing supportive care.

  • HCG and progesterone administration's effectiveness is uncertain.

  • Address raised luteinizing hormone issues with appropriate therapies.

  • For antiphospholipid syndrome, low-dose aspirin and heparin are effective to reduce loss.

Complications of Spontaneous Abortion

  • The complications may include:

    • Haemorrhage, infection (with potential for septic complications including endotoxic shock), and trauma from clinical abortions.

    • Psychological effects such as depression and grief surrounding miscarriages.

    • Increased likelihood of subsequent spontaneous abortion and risk of Rhesus sensitivity if prophylaxis is not administered.

    • Risk of disseminated intravascular coagulation (DIC).

Management Strategies for Various Abortions

  • Threatened: Notify medical personnel, verify fetal viability using ultrasound.

  • Inevitable: Use ultrasounds to determine abortion type; consider analgesics.

  • Incomplete: Hospitalization and potential D&C prior to 14 weeks; use pitocin or prostaglandins afterward.

  • Medical Treatment: Prostaglandin use (Cervagem) may facilitate miscarriage; mifepristone may enhance induction effects.

  • Surgical Treatment: Pre-procedure cervical preparation; ultrasonography for gestational age verification.

  • Antibiotic Treatment: Use antibiotics like erythromycin or metronidazole for identified infections; continue for five days.