Pfannenstiel Approach to the Pubic Symphysis

The Pfannenstiel approach provides direct anterior access to the pubic symphysis and superior pubic rami for open reduction and internal fixation of symphyseal diastasis and anterior pelvic ring injuries. Originally described by Hermann Pfannenstiel in 1900 for gynaecological procedures, it has become the standard anterior window for trauma surgeons treating APC pelvic ring injuries and combined acetabular fractures. The transverse suprapubic incision lies two fingerbreadths above the pubic crest and allows development of the space of Retzius after the bladder is decompressed. The rectus abdominis is either split in the midline through the linea alba or one head is released from the pubis. The critical deep structures are the bladder, the spermatic cord or round ligament, and the corona mortis vascular anastomosis on the superior pubic ramus. This approach is frequently extended into the modified Stoppa intrapelvic exposure for full anterior column and acetabular access.

Primary Indications:

• Symphyseal diastasis in APC II and APC III pelvic ring injuries requiring plate stabilisation
• Displaced superior pubic ramus fractures with anterior ring instability
• Combined anterior pelvic ring and acetabular fractures (transverse, T-type, anterior column)
• Revision surgery for symptomatic symphyseal nonunion or malunion
• Open book pelvic injuries with urological or bowel entrapment requiring direct access

Why This Approach is Chosen:

The Pfannenstiel incision provides the most direct and cosmetic anterior access to the pubic symphysis and medial superior rami. It allows excellent visualisation of the retropubic space after bladder decompression and can be extended laterally along the pelvic brim into the modified Stoppa approach without additional skin incisions. The transverse orientation respects Langer's lines and heals with an excellent cosmetic result compared with vertical midline laparotomy incisions.

Contraindications:

• Active infection or open wounds in the suprapubic region
• Previous lower abdominal surgery with dense adhesions (relative)
• Severe bladder injury requiring urological repair first (coordinate timing)
• Patient instability precluding anterior pelvic surgery

Alternative Approaches:

• Vertical midline laparotomy: when simultaneous abdominal exploration required
• Modified Stoppa (intrapelvic): for full anterior column and acetabular access through same skin incision
• Ilioinguinal approach: when lateral window needed for iliac wing or posterior column
• Percutaneous anterior ring fixation: for minimally displaced rami fractures in stable patterns

Bony Anatomy:

The pubic symphysis is a fibrocartilaginous joint between the medial ends of the superior pubic rami. The symphyseal disc is reinforced by the superior pubic ligament, arcuate (inferior) pubic ligament, and anterior pubic ligament. The superior pubic ramus extends laterally from the symphysis to the acetabulum, forming the anterior boundary of the pelvic brim. The pectineal line runs along the superior aspect of the ramus and is the attachment site for the pectineal ligament and the origin of the pectineus muscle.

Muscular Layers:

The anterior abdominal wall consists of skin, subcutaneous tissue, Scarpa's fascia, external oblique aponeurosis, internal oblique, transversus abdominis, transversalis fascia, and peritoneum. At the midline the rectus abdominis muscles are enclosed in the rectus sheath formed by the aponeuroses of the three lateral muscles. Below the arcuate line (approximately midway between umbilicus and pubis) the posterior rectus sheath is absent and the rectus lies directly on transversalis fascia.

Neurovascular Anatomy:

The rectus abdominis receives segmental innervation from the terminal branches of T7-T12 intercostal nerves that enter the lateral border of the muscle. There is no single dominant nerve supply, therefore splitting or releasing the rectus does not produce clinically significant denervation. The inferior epigastric vessels run on the posterior surface of the rectus and may be encountered during lateral dissection. The corona mortis crosses the superior ramus 4-6 cm lateral to the symphysis in 30-40 percent of individuals.

Retropubic Space of Retzius:

The space of Retzius is the extraperitoneal space between the pubic symphysis and bladder. It contains loose areolar tissue, the venous plexus of Santorini (deep dorsal vein complex), and is the plane developed during the Pfannenstiel approach after rectus mobilisation.

Deep Internervous Plane:

There is no true internervous plane in the Pfannenstiel approach. The rectus abdominis is supplied segmentally by the terminal branches of the lower six thoracic nerves (T7-T12). These nerves enter the lateral border of the rectus and travel medially within the muscle. A midline split through the linea alba or lateral release of one rectus head therefore does not denervate the muscle.

Superficial Dissection:

The skin incision is transverse and the subcutaneous tissue is divided in line with the skin. The anterior rectus sheath (linea alba) is incised vertically in the midline. The rectus muscles are either separated in the midline or one head is sharply released from the pubic crest. The transversalis fascia is divided and the space of Retzius is entered bluntly.

Structures at Risk in Each Layer:

Position: Supine on Radiolucent Table

Pre-positioning Checklist:

• Urinary catheter inserted and bladder decompressed before skin preparation
• Arms positioned safely (abducted less than 90 degrees, padded)
• Radiolucent table confirmed with full fluoroscopic access (inlet, outlet, obturator oblique, iliac oblique)
• C-arm positioned for pelvic imaging from the opposite side
• Prep and drape from umbilicus to mid-thigh, including both iliac crests

Positioning Details:

• Supine position with slight hip flexion (10-15 degrees) to relax the iliopsoas and rectus
• Bump under the sacrum if needed to elevate the pelvis for fluoroscopy
• Tourniquet not used
• Cell saver and cross-matched blood available for high-energy pelvic injuries

Alternative Positioning:

• Lithotomy position can be used if simultaneous perineal or rectal access is required (rare)
• Lateral decubitus if combining with posterior approaches (uncommon for isolated Pfannenstiel)

Key Bony Landmarks:

• Pubic symphysis - palpable midline prominence at the inferior border of the abdomen
• Pubic crest - superior border of the pubis, attachment of rectus abdominis
• Superior pubic ramus - palpable lateral to symphysis toward the acetabulum
• Anterior superior iliac spine (ASIS) - lateral limit of the incision
• Pectineal eminence - palpable prominence on the superior ramus

Key Soft Tissue Landmarks:

• Linea alba - midline raphe from xiphoid to pubis
• Rectus abdominis - palpable lateral to linea alba when contracted
• External inguinal ring - palpable superolateral to the pubic tubercle
• Spermatic cord - can be rolled under the skin in males lateral to the symphysis

Incision Planning:

• Transverse incision placed two fingerbreadths (approximately 2 cm) above the pubic crest
• Length typically 8-12 cm, extending from one rectus border toward the opposite ASIS if unilateral ramus access required
• The incision should be slightly convex inferiorly to follow the skin crease
• In obese patients the incision may need to be placed slightly higher to avoid the skin fold

Corona Mortis Injury Management:

• If injured: pack the space of Retzius, apply direct pressure, and ligate both ends. Consider interventional radiology embolisation if bleeding persists.
• Prevention: always identify the vessel on the ramus before plate application.

Modified Stoppa (Intrapelvic) Extension:

The Pfannenstiel incision is the superficial portion of the modified Stoppa approach. After entering the space of Retzius, release the rectus insertion completely if needed and develop the extraperitoneal plane along the pelvic brim. Elevate the iliopsoas from the anterior column and quadrilateral surface. This provides access to the entire anterior pelvic ring, anterior column, and acetabulum without a second skin incision.

Lateral Extension Toward Ilioinguinal:

Extend the incision laterally along the inguinal ligament to the ASIS. Develop the plane between the external oblique aponeurosis and the inguinal ligament to access the iliac wing and anterior column from the lateral window. This converts the approach into a limited ilioinguinal exposure.

Proximal Midline Extension:

If simultaneous laparotomy is required, extend the incision proximally in the midline through the linea alba to the umbilicus or beyond. This is rarely needed in isolated pelvic ring trauma.

Combined Posterior Approaches:

For APC III injuries with posterior ring disruption, the Pfannenstiel approach is combined with percutaneous or open posterior fixation (iliosacral screws, sacral bars, or posterior tension band plating) in the same or staged procedure.

Intra-operative Complications:

Post-operative Complications:

Immediate Post-operative:

• Neurovascular checks of both lower limbs
• Confirm urinary catheter is draining (watch for haematuria)
• Pelvic binder or external fixator if used for provisional stability
• DVT prophylaxis started within 12 hours unless contraindicated

Weight Bearing Protocol:

• Non-weight bearing or touch weight bearing on the affected side for 6-12 weeks depending on posterior ring stability
• Progression based on radiographic healing and pain
• Crutches or walker required

Range of Motion:

• Gentle hip flexion and abduction as pain allows
• Avoid aggressive hip external rotation in the first 6 weeks (protects symphyseal repair)
• Pelvic floor physiotherapy referral for dyspareunia or pelvic pain

Follow-up Schedule:

• 2 weeks: Wound check, suture removal
• 6 weeks: Radiographs (inlet/outlet), assess healing, progress WB if appropriate
• 12 weeks: Radiographs, confirm union, progress to full WB
• 6 months: Clinical and radiographic review, consider CT if nonunion suspected
• 1 year: Final review, discuss return to sport/work

DVT Prophylaxis:

• LMWH or aspirin per institutional protocol for minimum 4-6 weeks
• Consider extended prophylaxis in patients with limited mobility

The Pfannenstiel approach is used worldwide for symphyseal plating in APC pelvic ring injuries and as the anterior window for the modified Stoppa approach to acetabular fractures. Principles are convergent across examination systems (FRCS, FRACS, EBOT, ABOS).

Side-by-side principles (where guidance converges):

Registry / population evidence:

• APC II and III injuries comprise approximately 15-20 percent of pelvic ring fractures in high-energy trauma registries.
• Symphyseal plating through a Pfannenstiel approach achieves stable anterior ring fixation in greater than 90 percent of cases when combined with appropriate posterior stabilisation.
• Corona mortis injury rates have fallen from historical 10-15 percent to less than 3 percent in modern series with deliberate identification.

Global practice variation:

In high-resource settings, dedicated pelvic reconstruction plates and routine CT with 3D reconstruction are standard. In resource-limited settings, the same biomechanical principles are achieved with contoured reconstruction plates or even one-third tubular plates, and external fixation has a larger role for temporisation.

Consent (globally applicable):

Discuss bladder injury (1-3 percent), corona mortis bleeding requiring ligation or embolisation (2-5 percent), abdominal wall hernia (2-5 percent), chronic symphyseal pain or dyspareunia (10-20 percent), infection (2-5 percent), and the need for posterior ring stabilisation in APC III injuries.