A contracted pelvis is one where one or more diameters of the pelvis are reduced, leading to difficulty in vaginal delivery.
Types of Pelvic Contraction:
- Generalized Pelvic Contraction – All diameters are reduced.
- Anteroposterior (AP) Contraction – Narrowing of the inlet.
- Transverse Contraction – Narrowing of the mid-pelvis.
- Outlet Contraction – Shortened anteroposterior or transverse diameter of the outlet.
Etiology (Causes) of Contracted Pelvis
1. Congenital Causes:
- Genetic factors.
- Rickets (Vitamin D deficiency).
- Achondroplasia (Dwarfism).
2. Acquired Causes:
- Pelvic fractures or trauma.
- Previous pelvic surgeries.
- Poliomyelitis (Paralytic conditions affecting pelvic bones).
- Osteomalacia (Softening of bones due to calcium deficiency).
- Spinal deformities (Scoliosis, Kyphosis).
Classification of Contracted Pelvis (Caldwell-Moloy Classification)
|
Pelvic Type |
Features |
Incidence |
|
Gynecoid |
Round inlet, Ideal for vaginal delivery |
50% |
|
Android |
Heart-shaped inlet, Narrow pelvis |
20% |
|
Anthropoid |
Oval-shaped inlet, Long AP diameter |
25% |
|
Platypelloid |
Flattened pelvis, Wide transverse diameter |
5% |
Contracted pelvis is most commonly seen in Android & Platypelloid pelvis.
Clinical Features of Contracted Pelvis
- History of previous obstructed labor.
- Short stature (<150 cm).
- Narrow pubic arch.
- Prominent sacral promontory.
- High intertrochanteric diameter.
Diagnosis of Contracted Pelvis
1. Clinical Pelvimetry (Manual Assessment of Pelvic Dimensions):
- Diagonal Conjugate: Distance from sacral promontory to pubic symphysis.
- If <11.5 cm → Suggests pelvic contraction.
- Interischial Diameter (Bituberous Diameter): Normal = >8.5 cm.
- Sacral Curvature & Pubic Angle: Reduced sacral curve and narrow pubic arch suggest contraction.
2. Imaging Pelvimetry (Radiological Assessment):
- X-ray Pelvimetry: Measures pelvic dimensions.
- MRI Pelvimetry: Used for more precise measurements.
Effects of Contracted Pelvis on Labor
- Delayed engagement of fetal head.
- Malpresentations (Breech, Face, Transverse lie).
- Obstructed labor.
- Prolonged labor leading to maternal & fetal complications.
Management of Contracted Pelvis
1. Mild Contraction:
- Trial of labor if fetal size is appropriate.
- Continuous monitoring for signs of labor obstruction.
2. Moderate to Severe Contraction:
- Planned Cesarean Section (C-Section).
3. Absolute Contracted Pelvis (Severe Cases):
- Elective C-section mandatory.
- Avoid vaginal delivery to prevent obstructed labor & fetal distress.
Complications of Contracted Pelvis
Maternal Complications:
- Obstructed labor.
- Uterine rupture.
- Postpartum hemorrhage (PPH).
- Fistula formation (Vesicovaginal or Rectovaginal fistula).
Fetal Complications:
- Birth asphyxia.
- Intracranial hemorrhage.
- Neonatal sepsis (due to prolonged labor).
Summary Table: Contracted Pelvis
|
Feature |
Key Points |
|
Definition |
Pelvic diameters reduced, leading to obstructed
labor |
|
Types |
AP contraction, Transverse contraction, Outlet
contraction |
|
Causes |
Rickets, Trauma, Poliomyelitis, Spinal deformities |
|
Diagnosis |
Clinical pelvimetry, X-ray/MRI pelvimetry |
|
Complications |
Obstructed labor, Uterine rupture, Fetal distress |
|
Management |
Trial of labor (mild cases), C-section
(moderate/severe cases) |
Key Takeaways
- Contracted pelvis increases the risk of labor complications.
- Diagnosis is based on clinical pelvimetry & imaging.
- Severe cases require Cesarean delivery to prevent maternal & fetal risks.
