This electronic dissection is based on the surgical posterior approach to the kidney.
CC: Blood in urine.
HPI (history of present illness): HL is a 56 YO (year old) woman who came to the ED after discovering blood in her urine this morning. She denies any prior urinary tract infections. She reports no pain on urination, nor increased frequency. No fever or chills. No recent weight loss, but reports she fatigues more easily. She reports no other health concerns and cannot recall when she was last examined by a physician.
PMH (past medical history): No past medical or surgical history.
FH (family history):HL's grandparents moved to the U.S. from Sweden. Her paternal grandfather died of renal cancer.
SH (social history): Married with two grown children. Lives with her husband. Smokes 2 packs of cigarettes/day.
Meds: None
Allergies: NKDA (no known drug allergies)
Physical Exam: Hypertension (high blood pressure), gross hematuria (blood in urine)
WN (well nourished), WD (well developed) moderately obese female.
VS (vital signs): T (Temperature) = 101, HR (Heart Rate) = 72, RR (Respiratory Rate) = 12, BP (Blood Pressure) = 160/92
HEENT (head, eyes, ears, nose, and throat): Normal
Neck: No JVD (jugular vein distention), no lymphadenopathy, strong bilateral carotid pulse, no bruits.
Lungs: CTA (clear to auscultation) bilaterally.
Heart: RRR (regular rate and rhythm), S1/S2 normal, no murmurs, rubs, or gallops.
Abdomen: Soft, nontender, nondistended, no flank tenderness, no masses, (+) left renal bruit, no hepatosplenomegaly.
Extremities: Warm, well-perfused.
Neuro: A&Ox3 (alert and oriented to person, time, and place), CNII to CNXII grossly intact, reflexes normal and symmetric, strength and sensation normal.
Laboratory results: Notable for abnormal kidney function and mild anemia.
(Click on the question to show the answer.)
Which organ systems do the chief complaint and history of the present illness lead you to consider? Why?
Blood in the urine (hematuria) can result from kidney infection, cancer, or stones. Hematuria can also result from infection of the urinary bladder, especially in women (or in men with prostate disease). Some metabolic diseases can also cause blood in the urine.
So far, the differential diagnosis is fairly broad. How does the social and family history suggest leading candidates?
Renal cancer is suggested since there is a genetic component to renal cancer. Her grandfather's disease and Swedish heritage put her at greater risk. Smoking also increases her risk for renal cancer.
Which findings of the history & physical and lab results support your impressions thus far? What additional tests would be helpful?
Support: Hypertension (the kidney regulates blood pressure); Left renal bruit - a tumor could partially occlude the renal artery; abnormal kidney lab results.
Ambivalent: There is no palpable mass, but most renal tumors would be difficult to detect this way. Diagnostic imaging of the kidneys would be helpful.
Why would stenosis of the renal artery result in systemic hypertension?
A stenosis would result in lower blood pressure within the kidney. The kidneys react to low blood pressure by secreting a hormone (renin) that increases systemic blood pressure (RAAS, renin-angiotensin-aldosterone system).
Click this link to set up your session. Some structures have already been highlighted: Kidney (purple); Skeleton (white); Aorta (red); IVC (inferior vena cava) (Blue). Please dissect the left and right sides (a bilateral nephrectomy!).
Review the musculature of the back by selecting the Highlight tool (under the 3D window) and rolling your mouse over the various structures. Labels will appear at the top of the window. Starting superiorly in the midline, slide your mouse inferiorly to identify thoracic vertebrae, but notice that lumbar vertebrae cannot be identified this way.
Why can't the lumbar vertebrae be identified?
The kyphotic curve of the thoracic vertebral column enlarges the pleural cavity (increased lung capacity) and places the vertebral spines against the skin. The lordotic curve in the lumbar region places the vertebral column more centrally to better support the weight of the body with larger, stronger vertebral muscles. Consequently, soft tissue separates lumbar vertebral spines from the skin.
Use a line connecting the iliac crests to infer the position of the L4/L5 vertebral disc.
How would you perform a lumbar puncture between L3 and L4?
The lumbar vertebrae are more readily palpable by asking the patient to lay on their side in a fetal postion. This position flexes the vertebral column, and brings the vertebral spinous processes closer to the skin. Flexing the spinal column increases the distance between the laminar arches to facilitate insertion of a needle into the vertebral canal.
Note: If your screen is small you can enlarge the image by finding the "View" button in the top-left corner. Select 3D from the pulldown menu. (You can always return the the full view here).
Zoom the image and re-center the image on T12-L4. Select the Dissect tool under the 3D window. Identify and dissect the latissimus dorsi muscle and the thoracolumbar fascia (the aponeurosis of the latissimus dorsi) bilaterally.
What is the function of the latissimus dorsi muscle?
This extrinsic back muscle adducts and extends the arm.
Identify and dissect the erector spinae muscles (iliocostalis, longissimus, and spinalis) bilaterally.
What is the function of the erector spinae muscles?
These are intrinsic back muscles that can extend and laterally flex the vertebral column.
Identify and dissect the quadratus lumborum muscle bilaterally.
What is the function of the quadratus lumborum muscle?
This bodywall muscle acts on the ilium, 12th rib and vertebral column. It stabilizes the 12th rib during deep breathing, elevates the hip, and can extend and laterally flex the vertebral column.
Scan with your mouse to identify retro-peritoneal fat and dissect it bilaterally.
Select the Highlight tool under the 3D window. Identify the 12th rib and highlight the subcostal nerve just inferior to the rib bilaterally.
Go to the Index tab and search "ilio". Select, add, and highlight the iliohypogastric and ilioinguinal nerves bilaterally. Trace these nerves medially until they join to form the T12/L1 spinal nerves. Although the T12 branch and L1 spinal nerves join together, the iliohypogastric and ilioinguinal nerves are primarily L1 nerve fibers.
Note: To get back to the lesson, choose the Lessons tab from this same row of tabs within VHD.
To appreciate the view in 3D use the following method to rotate the image. Use the Ctrl or Command key together with the left or right arrow to slowly rotate the image back and forth in 5-degree increments.
Return to the posterior view. Dissect the psoas major muscle bilaterally.
What is the function of the psoas major muscle?
This bodywall muscle flexes the hip joint.
The kidneys are surrounded by two layers of fat. The pararenal fat lies outside the renal fascia of Gerota, while the perirenal fat and the kidney lie within the renal fascia. To minimize the risk of spreading the cancer, a surgeon should avoid cutting the renal fascia and remove the kidney, perirenal fat, and renal fascia as one unit.
Scan your mouse around to identify and dissect the pararenal fat bilaterally. Once you have done so, identify and dissect the perirenal fat. The kidneys are now revealed in purple.
Note that the left kidney is positioned more superiorly than the right kidney.
Rotate the image incrementally to appreciate the 3-dimensionality of the anatomy.
Observe that the kidneys are partially protected by the 12th ribs. Dissect the 12th rib bilaterally and the external intercostal muscles (and levatores costarum muscles) superior to them.
Identify and dissect the remaining muscles that obscure the kidneys. Of these, only the phrenic diaphragm attracts the attention of clinicians. You can safely forget about the others, because they are too small and insignificant to use for diagnostic testing and there is no disease specific to them.
Identify and highlight the suprarenal (adrenal) glands.
To see structures related to the kidney hilum, open the Systems tab. Open Muscles, Muscles of the back and select "Muscles of the back proper" and click Remove. These muscles rotate, flex, and extend the vertebral column.
On the left side of the body, work from superior to inferior to highlight the: renal artery, renal vein, renal pelvis, and renal accessory artery (an embryonic vestige that is seen on occasion).
Dissect vertebrae L1-L3.
To clarify this image, dissect the contents of the vertebral canal and various vertebral ligaments and veins. From the Index tab, search "ligament". For ease, select them all and click remove. From the Systems tab, open Nervous system, then Central nervous system, then select "Meninges" and click remove. Select "Spinal cord" and click Add & Highlight.
Identify the vertebral level where the spinal cord terminates by clicking on the key icon below the sagittal image. Press the command or control key + the up arrow until the entire spinal cord comes into view.
What is the vertebral level? What is the terminal region of the spinal cord called?
L2; Conus medullaris
In the 3D window, spinal nerves obscure the view of the most inferior portion of the spinal cord within the vertebral canal.
What is the collective name for the spinal nerves below L2 within the vertebral canal?
Cauda Equina
From the Index tab, search "nerve". Select and remove lumbar nerves L1-L5 bilaterally. Select and remove sacral nerves S1-5 bilaterally. Dissect the spinal cord.
Dissect the intervertebral discs, basivertebral veins, lumbar veins, and lymph nodes that obscure your view of the aorta and IVC. Notice the anomalous left renal vein that travels posterior to the aorta.
Now you can identify and highlight the ureter, extending from the renal hilum and traveling with the testicular artery and vein. Observe that the testicular artery stems from the aorta and the testicular vein drains into the renal vein on the left.
Note: To find all of these structures, you may have to rotate the image one or two clicks to the left or the right.
This would be a good time to rotate the image incrementally, back and forth to appreciate the structures in 3D.
If you have been using the 3D view, find the "View" button in the top-left corner and select Full from the pulldown menu.
In the 3D window click on the Planes button and select "Outline" in the transverse plane. Move the plane to the level of the kidney (you may have to zoom out to find the plane). The lower left cross-sectional window will show you this plane.
Manipulate the 2D windows to explore and trace the structures you highlighted in the posterior view of the 3D window. Take time to incrementally scroll through the cross-sections. In the transverse window, trace the left renal vein from the kidney to the IVC. To do this click the "Key" icon under the transverse window. Hold the command or control key as you click the up or down arrows. You will need to click through a number of slices. Identify the typical left renal vein traveling anterior to the artery and the anomalous vein you identified earlier.
Dissect the kidney. The vasculature of the kidney will remain. Manipulate the various 2D windows to reveal the cortex, medulla, and (with imagination) the major and minor calyces.
To remove the kidney, you will need to clamp the renal artery(ies) and vein. Which should you clamp first? Why?
Arteries are clamped first. If veins were clamped first, blood pressure would increase in the kidney.
Dissect the transversalis fascia and interperitoneal fat. (This will also remove the thin peritoneum, the lining of the peritoneal cavity.) Now for the first time you can see the various segments of the gastrointestinal tract.
The beauty of this procedure is that the surgeon avoids entering the peritoneal cavity. Why is this advantageous?
The postoperative complication of a peritoneal infection (peritonitis) is avoided.
Congratulations! Be sure to spend some time on this image. Scan the mouse around the various windows and peruse the anatomical relationships of the kidney.
Obviously, the surgeon would not remove the structures you just did. To avoid the back muscles and vertebral column, he or she would enter the retroperitoneal space just lateral to the quadratus lumborum muscle and approach the kidney posterolaterally. Needle biopsies would follow the same path. Trace this path in the transverse cross-section.
When performing this procedure a surgeon should be aware of the following important anatomical concepts: