The Retroperitoneal Space
Space behind the peritoneum in abdominal cavity is known as retroperitoneal space or retroperitoneum. Retroperitoneal organs are covered anteriorly (in front) by peritoneum and posteriorly by posterior (back) abdominal wall. Retroperitoneal space is divided in to upper and lowers retroperitoneal space. Organs and viscera are confined in either one of the two retroperitoneal spaces or entire upper and lower retroperitoneal space as described below-
A.Organs of Upper Retroperitoneal Space
a. Urinary System
- Adrenal Gland
b. Digestive System
- Lower end of esophagus
- Duodenum lower end
- Pancrease- Head, Neck and Tail of the Pancrease.
B. Organ of Lower Retroperitoneal Space
- Urinary Bladder.
C. Organs and Tissues Occupies Entire (Upper and Lower) Retroperitoneal Space
a. Circulatory System-
- Abdominal Aorta and Branches.
- Inferior Vena Cava and Branches.
- Vessels of Kidney, Mesentery, Pancreas and Bladder.
b. Digestive System-
- Ascending and Descending Colon
c. Nervous System-
- Spinal Nerve and Nerve Plexus
- Sympathetic Nerves
d. Lymphatic System
- Lymph nodes
- Lymph vessels
e. Adipose Tissue or Fatty Tissue
f. Paravertebral Muscles
g. Spinal Nerve and Nerve Plexus
Types of Retroperitoneal Mass or Tumor
Retroperitoneal diseases and types of retroperitoneal mass or tumor are as follows-
A. Retroperitoneal Hematoma
- Injuries Caused by Accident- Injuries of lower back following work accident or automobile accident may cause retroperitoneal hematoma.
- Injuries Caused by Fall- Other causes of retroperitoneal hematoma are sports injury, domestic fall or post surgical bleeding.
- Post Surgical Bleeding- Bleeding following surgery of kidney, pancreas or colon.
B. Retroperitoneal Abscess
- Penetrating Injury- Infection of penetrating injury of lower back like knife injury or gun shot wound causes abscess formation and may spread in adjacent tissue or stay within the capsule.
- Psoas abscess can spread into lower back and become difficult to treat with antibiotics and may need surgery.
C. Retroperitoneal Lymphadenopathy
- Metastasis and lymphatic spread of cancer of retroperitoneal viscera causes enlargement of lymph nodes in retroperitoneal space.
- Enlarged multiple lymph nodes causes pressure on nerves and tubular organs resulting in pain or obstruction of tubular structure like ureter and duodenum or colon.
D. Malignant Retroperitoneal Neoplasm
a) Mesenchymal Neoplasm- Most common mesenchymal malignant neoplasm observed in retroperitoneal space is Liposarcoma and Leomyosarcoma.
- Liposarcoma is a malignant cancer of fatty cells (adipose tissue) known as atypical adipocytes and lipoblasts.
- Aggressive cancer is well-differentiated tumor and metastasizes rapidly.
- Liposarcoma has the worst prognosis.
- Liposarcoma grows wider as a bulky neoplasm.
- Tumor cells spreads in surrounding soft tissue as an appendage of the tumor.
- Leomyosarcoma is very aggressive neoplasm like Liposarcoma.
- Tumors metastasize in to surrounding tissue as well as distant organs.
- Tumor causes multiple complications like bleeding and nerve lesions following infiltrating into vessels and nerves.
- Malignant tumor derives from fibrous connective tissue of retroperitoneal space.
- The grades of neoplasm or malignancy is divided as low grade, intermediate or high grade malignancies.
- Intermediate and high grade tumor metastasize through blood vessels to distant tissue or organs.
- Neurofibrosarcoma is a malignant nerve cell tumor and is often seen in 1% of all patients of nerve cell neoplasm.
d) Cancer of Pancreas
- Pancreatic cancer may develop from head, body or tail of the pancreas. Tumor mass is malignant and spreads in retroperitoneal space. Tumor mass obstructs blood vessels and bowel causing ischemic and bowel obstruction symptoms.
e) Kidney Tumor
- Renal cell carcinoma spreads in retroperitoneal space and often causes pressure symptoms on surrounding viscera and blood vessels.
- Extremely malignant and metastasize to distant soft tissue and bones.
f) Cancer of Duodenum
- Adenocarcinoma of duodenum is rare compared to colon cancer.
- Cancer of polyp is also occasionally diagnosed causing least retroperitoneal symptoms of abnormalities.
g) Colon Cancer
- Adenocarcinoma of ascending or descending colon causes bowel obstruction and infiltration of retroperitoneal space.
- The tumor mass causes obstruction of colon, surrounding blood vessels and pressure on nerve resulting in symptoms of obstruction, ischemia (lack of blood supply) and pinch nerve.
E) Benign Neoplasms-
- Benign tumor is covered by capsule. Growth of the tumor is slow and most of the symptoms are related to complications caused by tumor pressing on surrounding soft tissue. Compression and displacement of viscera causes symptoms of visceral obstruction, ischemia and nerve lesions.
- Example of benign retroperitoneal tumors are as follows-
- Gastrointestinal Stromal Tumors
- Schwannoma- Benign nerve sheath tumor.
- Pheochromocytoma- Benign tumor of medulla of adrenaline gland.
Signs and Symptoms for Retroperitoneal Mass or Tumor
General Symptoms of Retroperitoneal Mass or Tumor
- Loss of Appetite
- Weight Loss
- Retroperitoneal Pain or Back Pain
Specific Symptoms and Signs of Retroperitoneal Mass or Tumor
- Flank Pain- Flank pain is caused by kidney tumor mass.
- Retroperitoneal Pain- Retroperitoneal abscess, hematoma, Liposarcoma, Leomyosarcoma and Fibrosarcoma causes retroperitoneal pain.
- Abdominal Pain- Periumbilical abdominal pain is caused by pancreatic cancer, duodenal cancer and colon cancer.
- Radicular Pain- Pinch of the lumbar nerve or plexus causes severe radicular pain. Pinch is often caused by retroperitoneal tumor mass or hematoma.
- Back Pain- Severe back pain often follows pressure from hematoma, abscess or tumor mass over muscles, facet joint and vertebral column.
Obstruction of Viscera and Tubular Organs-
- Nausea and Vomiting- Caused by obstruction of duodenum, ascending and descending colon
- Nausea Only- Kidney carcinoma and pancreatic carcinoma.
- Colic Pain- Caused by cancer of kidney, ureter, colon and duodenum.
- Constipation- Caused by cancer of colon and duodenum.
- Urinary Retention- Caused by cancer of ureter and urinary bladder
Compression of Aorta
- Hypertension- Compression of abdominal aorta causes hypertension, which often does not respond to antihypertensive medications. Symptoms of hypertension are as follows-
- Ringing in Ear
- Blur Vision
- Occasional Confusion.
- Renal Insufficiency- Insufficient blood supply to kidney causes increased secretion of angiotensin resulting in hypertension and kidney failure.
- Mesenteric Ischemia- Compression of aorta or direct obstruction of mesenteric blood vessels reduces mesenteric blood supply. Reduced blood flow through mesenteric artery causes ischemic changes of bowel and following symptoms-
- Nausea and Vomiting
- Increased Heart Rate
- Blood in Rectum
- Intermittent Claudication- Intermittent claudication is caused by decreased blood flow to lower extremity. Following symptoms are observed-
- Muscle Cramps
- Leg Muscle Pain
- Weakness and Inability to Climb
Compression of Vena Cava
- Compression of inferior vena cava causes less return of the blood to heart and more retention of blood in peripheral tissue.
- Symptoms Are As Follows-
- Edema of Feet
- Intense Pain In The Right Hand Side
- Muscle twitching
- Low Blood Pressure
- Nerve lesions are caused by irritation and pinch of spinal nerve and nerve plexus.
- Symptoms Are As Follows-
- Tingling and Numbness in Leg
- Weakness of the Legs
- Hematuria is caused by cancer of kidney, urinary bladder and ureter.
- Retroperitoneal abscess causes pressure symptoms on ureter, colon and urinary bladder resulting in obstruction of urinary flow and retention.
Investigations to Diagnose Retroperitoneal Mass or Tumor
- CT Scan- Provides better picture than plain X-Ray and understanding of the tumor mass.
- CT Scan Following Retrograde Pyelography provides information of bladder, ureter and kidney.
- CT Scan Following Barium Swallow provides information of internal complication of duodenum, intestine and colon caused by tumor mass.
- Magnetic Resonance Imaging (MRI) for Retroperitoneal Mass or Tumor
- Provides information of vascular structures close to tumor
- Cystic tumor mass
- Necrotic tumor mass
- Enhancing tumor compressing surrounding soft tissue.
- CT Guided Biopsy- The study provides diagnosis of type of tumor and also if tumor is malignant or benign in character.
- Vascular Study- Vascular studies are performed to evaluate blockade of arteries and vein from external tumor mass. Most common studies are as follows-
- Ultrasound- Ultrasonography helps to diagnose visualized retroperitoneal tumor mass and evaluate external damage of retroperitoneal organ like pancrease, kidney, ureter and bladder.