Scenario: A 13 y/o teen presenting for a 3 month f/u dx of PSGN; persistent hematuria, low C3 levels, so based on these findings, what dx would you consider? What labs/studies are used to confirm dx?

In PSGN, Serum complement levels (C3) are usually low due to its consumption in the inflammatory reaction. However as you recover from APSGN, complement C3 levels return to normal within 6-8 weeks. Persistently low C3 levels indicate an etiology other than APSGN and may warrant a renal biopsy, especially if there is continued hematuria and/or proteinuria. Gross hematuria will generally resolve within 1 to 2 weeks. Microscopic hematuria may persist for a 6months or more.

Serum C3 and C4 levels — The measurement of C3 and/or C4 can assist in the diagnosis of certain diseases (especially SLE), as well as in monitoring the course of the disease. Other diseases featuring autoantibodies leading to immune complex formation are the antiphospholipid syndrome, mixed cryoglobulinemia, Sjögren syndrome, and membranoproliferative glomerulonephritis. Low C4 and C3 or low C3 alone can indicate the presence of any of these disorders. On the other hand, increasing levels indicate a response to treatment.

DDx

• IgA Nephropathy: usually occurs after an upper respiratory tract or gastrointestinal infection, but it differs from PSGN in the shorter latency period it takes to appear after the episode of infection. Only confirmed by kidney biopsy.
• Membranoproliferative glomerulonephritis: also presents with a nephritic picture and hypocomplementemia following respiratory tract infection. Complement levels take a longer time to return to normal than in PSGN or persistently low C3 levels. Immunofluorescence microscopy and/or electron microscopy from biopsy to diagnose.
• Lupus nephritis: sometimes PSGN presents with a picture similar to lupus nephritis. Laboratory testing for antibodies specific to each of the diseases can help in the diagnosis. Positive ANA, anti-dsDNA, antiphospholipid antibodies, ESR/CRP
• Dense deposit disease (DDD) and C3 glomerulonephritis (C3GN) are rare forms of glomerulonephritis that affect both children and adults. Both diseases result from abnormal regulation of the alternative complement pathway and are now classified under the heading of “C3 glomerulopathies.” The clinical presentation is variable, and the diagnosis is made by immunofluorescence examination and electron microscopy of a kidney biopsy specimen, supplemented by studies of the complement system.

 

Scenario: 2 y/o boy develops emesis and intermittent abdominal pain x 1 day w/ several small partially formed stools. Parents were not overly concerned since child seemed fine between pain episodes. Today he has persistent bilious emesis and several bloody stools. He is tachycardic and febrile with diffuse abdominal tenderness and vague tubular mass in the RUQ. What are your DDx? What Diagnostic studies are needed?

Intussusception: is when a part of the intestine folds into another section of intestine, leading to an obstruction. Commonly referred to as telescoping, and is the most common cause of intestinal obstruction in infants and young children (6 months – 4 years). Definitive diagnosis requires imaging such as an US, which is the method of choice, and it may reveals a classic bulls-eye, donut or target sign which represents the telescoped intestine. Per UpToDate, abdominal plain film or CT can also be utilized to rule out perforation and identify causes but should be weighed against radiation exposure. A barium or air enema is both diagnostic and therapeutic as it can be used to unfold the intussusception.

Meckel’s diverticulum: which is an abnormal outpouching of gastrointestinal tissue, that sticks out of the ileum and into the peritoneal cavity Occasionally, the diverticulum can invert and stick back into the intestine, leading to intussusception. Patients can present with a variety of GI symptoms but typically c/o painless rectal bleeding. The most sensitive test is a Meckel radionuclide scan also known as the Meckel’s scan. It is a nuclear study done by injecting technetium-99m which is absorbed by the ectopic gastric mucosa allowing for visualization of the Meckel’s diverticulum. A CT scan of the abdomen and pelvis may show evidence of inflammation or obstruction at the diverticulum. More invasive methods include mesenteric angiography as well as exploratory laparoscopy

Midgut volvulus: A volvulus is where the intestines twist upon themselves and can occur at any age. However, it is more frequent in children and infants. Plain films may suggest partial duodenal obstruction or perforation. Upper GI series can shows incomplete rotation and the duodenum may show a corkscrew effect diagnosing volvulus or complete duodenal obstruction, with the small bowel looping entirely on the right side of the abdomen.

Acute gastroenteritis: From viral, bacterial or parasitic causes should be included. most common cause in infants younger than 24 months old is rotavirus, after 24 months of age, Shigella displaces it to second most common. Diagnostics are used to help rule out other causes of the patient’s symptoms. Complete blood counts may reveal a mild leukocytosis in a patient with viral gastroenteritis. Other serum inflammatory markers may also show mild elevation. Patients who are suffering from significant dehydration may demonstrate hemoconcentration on complete blood count testing as well as electrolyte disturbances on chemistry panels. Dehydration may also present as acute kidney injury, evidenced by changes in the BUN and creatinine on chemistry panel. Patients with diarrhea have the risk of dehydration; initial evaluation is to identify the presence and severity. Microscopic stool examination and culture can narrow the causative agent. Cultures should be done as promptly as possible in children that present leukocytes in the microscopic evaluation and have bloody diarrhea.

Appendicitis: is an acute inflammatory process involving the appendix. It can be a surgical emergency and one of the most common causes of abdominal pain, particularly in children. It should be considered in any patient with acute abdominal pain without prior appendectomy. As for evaluation an increase in WBC count with a left shift can indicate inflammation. Use of ultrasound is increasing, particularly in children in whom the risks of ionizing radiation are greatest. MRI is a reliable modality which is particularly useful for children when ultrasound is inconclusive.

 

Compartment Syndrome

How to measure intracompartmental pressure? At what pressure and clinical findings is intervention necessary? What is the intervention? And what are long term complications?

Compartment pressures are not always needed for diagnosis of acute compartment syndrome. However compartment pressures are measured based on patients risk factors and clinical findings such as a painful tense muscle compartment to aid in diagnosis. Notable findings of compartment syndrome are pain out of proportion to injury, pain with passive stretch of muscles, and a tense compartment with a “wood like” feeling.

To measure intracompartmental pressure, a handheld manometer is most commonly used. It works by measuring the resistance after a small amount of saline is injected into the compartment. Another option is a slit catheter that is inserted into the compartment and connected to an arterial line transducer to measure the pressure. This method allows for continuous monitoring and may be more accurate but air bubbles can lead to false low readings and the transducer must be at catheter level.

Normal pressure within compartments is between 0 – 8 mm Hg. Certain clinical findings also correlate to pressure readings. Such as capillary blood flow is compromised with a 25-30 mmHg increase compared to MAP, pain develops when tissue pressure is 20-30 mmHg, and ischemia occurs when tissue pressure reaches diastolic pressure. The perfusion pressure of a compartment, or delta pressure of compartment is defined as the difference between diastolic blood pressure and intracompartmental pressure. If the delta pressure is < 30 mmHg then a fasciotomy is required. Thus intervention is necessary if the measured intracompartmental pressure is above 30 mmHg, or if the delta pressure is < 30 mmHg.

A surgical fasciotomy is when one or more incisions to the fascia/tissue that surrounds the area is cut open to relieve the intracompartmental pressure. Ideally it should be done within six hours of injury, and not recommended after 36 hours. This is because the rate of infection and amputation has increased and irreversible damage may occur and a fasciotomy would not be beneficial. Afterwards swelling should dissipate and a skin graft is needed for closure. Patients should still be monitored as complications may arise such as residual pain, contractures, infection, nerve damage, acute kidney failure, rhabdomyolysis, and death. Delays in diagnosis and treatment of acute compartment syndrome can significantly increase the morbidity and mortality after a fasciotomy. Muscle weakness may persist in the affected limb along with chronic nerve dysfunction and functional deficits.

Resources:

1. https://www.uptodate.com/contents/acute-compartment-syndrome-of-the-extremities
2. https://www.uptodate.com/contents/lower-extremity-fasciotomy-techniques?sectionName=OUTCOMES