Contracture pelvis by Dutta obtrestic
Dutta obstetrics contracture pelvis types diagonal conjugate management
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contracted pelvis types inlet outlet midpelvis obstetrics diagram
A series of four postoperative anteroposterior, inlet, and outlet pelvic X-rays demonstrating radiographic pelvimetry measurements using the Colcher-Sussman technique. The images show a pelvis with orthopedic hardware, including sacroiliac screws and pubic symphysis plating, indicating prior surgical fixation. Frame A (Transverse Inlet Diameter) shows a horizontal blue line representing the widest diameter of the pelvic inlet between the iliopectineal lines. Frame B (Anteroposterior Distance) illustrates a vertical midline from the anterior pubic symphysis to the sacrum on an inlet view. Frame C (Intertuberous Distance) depicts a transverse line at the pelvic outlet between the inferior margins of the ischial tuberosities. Frame D (Interspinous Distance) shows the mid-pelvic transverse diameter measured between the ischial spines. These diagnostic images are used in orthopedics and obstetrics to assess pelvic dimensions and symmetry following pelvic ring fractures and surgical reconstruction.
This diagnostic image is an axial Maximum Intensity Projection (MIP) reconstruction from a computed tomography (CT) scanopelvimetry. It provides a cross-sectional view of the female pelvic inlet and outlet for obstetric assessment. The central feature is the sacrum, appearing as an oval bony ring, flanked laterally by the iliac and ischial bones of the pelvis. Orientation is clearly marked with 'R' for the patient's right and 'L' for the patient's left. A linear measurement is demonstrated using a horizontal calliper line connecting the inner margins of the ischial bones. This line measures the median transverse diameter, which is annotated with a numerical value of 113 mm. Technical metadata in the upper right corner indicates a scale of '5mm/div' and the absence of a digital filter ('Filtre: Aucun'). This imaging modality is primarily used in clinical obstetrics to evaluate for pelvic narrowing and assess the adequacy of the birth canal for vaginal delivery.
This medical illustration consists of three panels (a, b, and c) showing 3D-rendered diagnostic images of the human pelvis, used to demonstrate orthopedic surgical planning. The panels present different fluoroscopic-style views: (a) Pelvic inlet view, (b) Pelvic outlet view, and (c) Obturator outlet view. Each image features a volume-rendered model of the bony pelvis, including the ilium, ischium, pubis, and the proximal femur with the acetabulum. Overlaid on the right side of the pelvis are parallel red lines illustrating the 'osseous corridor' for an anterior column acetabular screw. The lines represent the precise intraosseous trajectory from the gluteus medius eminence above the acetabulum, extending through the superior pubic ramus toward the pubic tubercle. This diagram serves as an educational guide for surgeons to visualize screw placement for acetabular fracture fixation, highlighting the safe anatomical pathway to avoid cortical penetration or articular surface violation.
Two anteroposterior plain radiographs of the human pelvis demonstrating specific trauma-focused projections: (a) an outlet view and (b) an inlet view. The images reveal a significant disruption of the anterior pelvic ring, characterized by a pubic symphysis diastasis measuring approximately 5.2 cm. In the inlet view (b), there is also visible anterior widening of the left sacroiliac (SI) joint, indicating a disruption of the posterior pelvic arch. These radiographic findings are consistent with an unstable pelvic ring injury, likely an Anteroposterior Compression (APC) Type II or III injury according to the Burgess-Young classification system. The outlet view specifically assists in evaluating craniocaudal displacement and sacral morphology, while the inlet view highlights the anteroposterior translation and rotational deformity of the hemipelvis. These projections are critical in orthopedic trauma for assessing pelvic stability and planning surgical fixation.
Contracted Pelvis - DC Dutta's Textbook of Obstetrics
Definition
- Inlet: Obstetric conjugate (OC) < 10 cm, OR transverse diameter < 12 cm
- Midpelvis: Interspinous diameter < 9.5 cm
- Outlet: Intertuberous diameter < 8 cm (bituberous < 8 cm)
Classification
A. According to the Plane Involved
| Plane | Contracted When |
|---|---|
| Inlet contraction | OC < 10 cm or transverse < 12 cm |
| Midpelvic contraction | Interspinous diameter < 9.5 cm |
| Outlet contraction | Intertuberous (bituberous) < 8 cm |
| Generally contracted pelvis | All planes uniformly reduced |
B. According to Degree of Contraction (Inlet)
| Degree | True Conjugate | Clinical Significance |
|---|---|---|
| Minor | 9-10 cm | Minor disproportion; spontaneous vaginal delivery often possible |
| Moderate | 8-9 cm | Moderate disproportion |
| Severe | 6-8 cm | Marked disproportion |
| Extreme (Absolutely contracted) | < 6 cm | Vaginal delivery impossible even after craniotomy; bimastoid diameter (7.5 cm) cannot be crushed |
C. According to Pelvic Architecture (Caldwell-Moloy Classification)
- Gynaecoid - Normal female pelvis; inlet is round/oval
- Android - Male-type; narrowed fore-pelvis, funnel-shaped; worst for labour
- Anthropoid - Oval AP inlet; long AP, narrow transverse
- Platypelloid - Flat pelvis; short AP, wide transverse
Causes (Etiology)
General Causes
- Nutritional: Rickets (most common historically), osteomalacia
- Hormonal: Delayed puberty, pituitary disorders
Spinal Causes
- Scoliosis, kyphosis, kyphoscoliosis
- Spondylolisthesis (forward slip of L5 on S1 - reduces AP diameter of inlet)
- Lumbar lordosis
Pelvic Causes
- Rickets - causes flat (platypelloid) pelvis
- Osteomalacia - causes beak-shaped pelvis (triradiate)
- Pelvic tumors or exostoses
- Paget's disease
Lower Limb Causes
- Dislocation of one or both hips
- Atrophy of one or both lower limbs
- Hip joint disease (causing asymmetric/oblique contraction)
- Coxalgic pelvis
Pelvic Measurements (Key Conjugates)
| Diameter | Measurement | Normal Value |
|---|---|---|
| True (anatomical) conjugate | Upper inner border of symphysis to sacral promontory | 11 cm |
| Obstetric conjugate | Most prominent inner point of symphysis to sacral promontory | 10 cm (minimum safe = 10 cm) |
| Diagonal conjugate | Lower border of symphysis to sacral promontory | 12 cm |
| Obstetric conjugate from DC | DC - 1.5 to 2 cm | ~10 cm |
The diagonal conjugate (DC) is the only AP diameter measurable clinically. The obstetric conjugate is computed as DC - 1.5 to 2 cm depending on symphysis height, thickness, and inclination.
Asymmetrical (Obliquely Contracted) Pelvis
Mechanism of Labor in Contracted Pelvis (Vertex)
With Inlet Contraction:
- The head may be deflexed or malpositioned at the brim
- Asynclitism (lateral tilting of head) occurs to negotiate the brim - anterior asynclitism (Naegele) or posterior asynclitism (Litzmann)
- Caput succedaneum forms but is not excessively large
- Once the head negotiates the brim, the cavity and outlet usually pose no problem
With Midpelvic/Outlet Contraction:
- Arrest of descent at the midpelvis
- Persistent occiput posterior or transverse position
- Deep transverse arrest is common
- Obstructed labor with risk of uterine rupture
Diagnosis of Contracted Pelvis
Antenatal
- History: Past obstetric history, nutritional deficiencies, rickets, limb/spinal deformity
- General examination: Height < 145 cm (suspect contracted pelvis), body build, spinal/limb deformities
- Abdominal examination: Non-engagement of head at term in primigravida (floating head sign), prominent lower pole of fetus
Clinical Pelvimetry
- Intercristal diameter: 28 cm
- Interspinous diameter: 26 cm
- External conjugate (Baudelocque's diameter): 20 cm
- Palpate forepelvis - check if round or V-shaped
- Measure diagonal conjugate - normally cannot reach the sacral promontory (> 12.5 cm). If felt, pelvis is contracted. Subtract 1.5 cm to get OC
- Note any sacral promontory protrusion
- Height, thickness, inclination of symphysis
- Shape and inclination of sacrum
- Ischial spines - if both can be touched simultaneously by two fingers, interspinous diameter ≤ 9.5 cm (inadequate)
- Sacrosciatic notch - if sacrospinous ligament < 2.5 finger breadths, notch is narrow
- Subpubic angle - normally admits 2 fingers (90°); < 90° is narrow
- Bituberous diameter - fist test (< 8 cm = contracted)
Radiological Pelvimetry
- CT pelvimetry (lowest radiation, most accurate) or MRI
- Lateral X-ray (Colcher-Sussman technique)
- Used when clinical findings are borderline or after failed trial labor
Diagnosis of Cephalopelvic Disproportion (CPD)
At the Brim:
- Non-engagement of head at term (primigravida)
- Floating head in early labor
- Munro-Kerr test: With patient in lithotomy, examiner's hand presses the fetal head into the pelvis while the other hand feels per abdomen - if head does not enter brim, disproportion likely
- Muller's test / Muller-Hillis maneuver: Fundal pressure applied; if head does not descend into the pelvis, CPD suggested
During Labor:
- Failure of engagement/descent despite good contractions
- Prolonged labor
- Excessive caput and molding
- Bandl's ring formation (pathological retraction ring - ominous sign of impending rupture)
Effects of Contracted Pelvis on Pregnancy and Labor
| Phase | Effects |
|---|---|
| Pregnancy | Unstable lie, malpresentation, non-engagement at term |
| Labor - mother | Prolonged labor, uterine dysfunction, obstructed labor, uterine rupture, fistula formation (VVF, RVF), PPH, sepsis |
| Labor - fetus | Birth asphyxia, intracranial hemorrhage, stillbirth |
Management
Management of Inlet Contraction
- Allow spontaneous labor; vaginal delivery usually possible
- Careful monitoring
-
Induction of labor - 2-3 weeks before EDD in selected multigravida with minor-moderate contraction and previous history of difficult vaginal delivery
-
Elective Cesarean Section at term - Indications:
- Major degree of inlet contraction
- Moderate contraction + unfavorable factors (elderly primigravida, precious baby, malpresentation, poor obstetric history, fetal macrosomia)
- OC < 7.5 cm (absolute indication)
-
Trial of Labor - For borderline cases (OC 8.5-10 cm)
Trial of Labor (Dutta)
- OC between 8.5 and 10 cm (borderline pelvis)
- Vertex presentation, well-flexed
- Average-sized fetus (estimated < 3.5 kg)
- No other complication
- Facilities for immediate CS available
- Informed consent
- Spontaneous onset of labor preferred
- Continuous monitoring (FHR, uterine contractions)
- ARM (artificial rupture of membranes) when head is at or near the brim
- Watch for: descent of head, cervical dilation, fetal condition
- Maximum time allowed: 12-18 hours of active labor (some texts say up to 6-8 hours after full dilation)
- Arrest of descent despite good contractions
- Fetal distress
- Bandl's ring formation
- Excessive molding
- No progress after adequate trial
Midpelvic and Outlet Disproportion
- Midpelvic contraction (interspinous < 9.5 cm): Deep transverse arrest - may attempt assisted vaginal delivery (ventouse/forceps) if head is low; otherwise CS
- Outlet contraction alone (bituberous < 8 cm): Symphysiotomy (rarely done today) or CS; Schuchardt incision may give extra room
Pelvimetry: Normal Values Summary (Dutta)
| Diameter | Normal |
|---|---|
| Obstetric conjugate | ≥ 10 cm |
| Diagonal conjugate | ≥ 12 cm |
| Transverse inlet | ≥ 12 cm |
| Interspinous (midpelvis) | ≥ 10 cm |
| Intertuberous (outlet) | ≥ 8 cm |
| Subpubic angle | 90°-100° |
- Diagonal conjugate is the only clinically measurable AP diameter (DC - 1.5 to 2 cm = obstetric conjugate)
- Absolutely contracted pelvis: OC < 6 cm - even craniotomy won't help (bimastoid = 7.5 cm)
- Floating head at term in primigravida = suspect contracted pelvis until proven otherwise
- Bandl's ring = danger sign of impending uterine rupture in obstructed labor
- Trial of labor is for OC 8.5-10 cm with vertex, average fetus, no complications
- Rickets → flat (platypelloid) pelvis; Osteomalacia → triradiate/beak pelvis; Spondylolisthesis → reduced AP inlet