The Greater Omentum: An Integral Structure with Surgical Importance

The greater omentum, also known as the gastrocolic omentum, is a double sheet of peritoneum that hangs down like an apron overlying loops of intestine. It is made up of four layers, two of which descend from the greater curvature of the stomach and are continuous with the peritoneum on the anterior and posterior surfaces of the stomach. The other two layers run between the anterior layers and the transverse colon, loosely blending with the peritoneum on the anterior and posterior surfaces of the colon and the transverse mesocolon above it.

Contrary to the belief that it has no surgical importance, the greater omentum is of paramount surgical importance. Surgeons use it to buttress an intestinal anastomosis or in the closure of a perforated gastric or duodenal ulcer. It also attempts to limit the spread of intraperitoneal infections, earning it the nickname great policeman of the abdomen. The greater omentum is supplied by the right and left gastric arteries, and its blood supply may be cut off if it undergoes torsion.

Furthermore, the greater omentum is often found plugging the neck of a hernial sac, preventing the entry of coils of the small intestine and strangulation of the bowel. In an acutely inflamed appendix, the omentum adheres to the appendix and wraps itself around the infected organ, localizing the infection to a small area of the peritoneal cavity. However, in the first two years of life, the greater omentum is poorly developed and less protective in young children.

In conclusion, the greater omentum is an integral structure with significant surgical importance, providing access to the lesser sac and attempting to limit the spread of intraperitoneal infections.

Updated Guidance on Death Certification in England and Wales

The guidance on death certification in England and Wales was recently updated in March 2022. One significant change was the extension of the period of time for seeing a patient before death from 14 days to 28 days. While this may be an important learning point for doctors, it may not necessarily appear in the RCGP exam as candidates will be tested on guidance that applies to all parts of the UK, including Scotland. However, it is still useful information for doctors working in England and Wales to be aware of. The UK government has provided guidance for doctors completing medical certificates of cause of death in England and Wales, which can be accessed for further information.

Differentiating Subtypes of Optic Neuritis

Optic neuritis is a condition that involves inflammation of the optic nerve, which can cause vision loss and other symptoms. However, there are several subtypes of optic neuritis that can present differently.

Neuroretinitis is a subtype of optic neuritis that involves both the retina and optic disc. A macular star pattern of lipid exudates may be present in the macula.

Papillitis is another subtype of optic neuritis that is characterized by swelling of the optic disc.

Papilloedema, on the other hand, is optic disc swelling that is typically caused by increased intracranial pressure.

Post-viral demyelination is a subtype of optic neuritis that can occur after a viral illness.

Retrobulbar neuritis is a subtype of optic neuritis where the optic disc is not affected.

It is important to differentiate between these subtypes of optic neuritis in order to determine the appropriate treatment and management plan.

Common Skin Conditions: Causes, Symptoms, and Treatments

Acne Rosacea:
Acne rosacea is a chronic skin condition that typically affects women and people with fair skin between the ages of 30-50. The exact cause is unknown, but environmental factors such as alcohol, caffeine, heat, and stress can aggravate the condition. Symptoms include a persistent erythematosus rash on the face, particularly over the nose and cheeks, with associated telangiectasia. Treatment involves lifestyle modifications and pharmacological interventions with topical or oral antibiotics.

Acne Vulgaris:
Acne vulgaris is an inflammatory response to Propionibacterium acnes, a normal skin commensal. It commonly affects adolescents and presents with a variety of lesions ranging from comedones to cysts and scars. It predominantly affects areas with high concentrations of sebaceous glands, such as the face, back, and chest.

Discoid Lupus Erythematosus:
Discoid lupus erythematosus is a cutaneous form of lupus erythematosus that affects sun-exposed areas of the skin. It typically presents in women between the ages of 20-40 and presents as red patches on the nose, face, back of the neck, shoulders, and hands. If left untreated, it can cause hypertrophic, wart-like scars.

Pityriasis Rosea:
Pityriasis rosea is a self-limiting skin condition that affects young adults, mostly women. It presents with salmon-pink, flat or slightly raised patches with surrounding scale known as a collarette. The rash is usually symmetrical and distributed predominantly on the trunk and proximal limbs.

Psoriasis:
Psoriasis is an autoimmune skin condition that presents with red scaly patches on the extensor surfaces of the limbs and behind the ears. Treatment involves topical or systemic medications to control symptoms and prevent flares.

The ASA (American Society of Anesthesiologists) score is used to assess a patient’s suitability for surgery. A patient is categorized as ASA 2 if they have a mild systemic illness that does not affect their daily activities. This may include conditions such as being a smoker, consuming alcohol socially, being pregnant, having a BMI between 30 and 40, having well-managed diabetes or hypertension, or having mild lung disease.

The American Society of Anaesthesiologists (ASA) classification is a system used to categorize patients based on their overall health status and the potential risks associated with administering anesthesia. There are six different classifications, ranging from ASA I (a normal healthy patient) to ASA VI (a declared brain-dead patient whose organs are being removed for donor purposes).

ASA II patients have mild systemic disease, but without any significant functional limitations. Examples of mild diseases include current smoking, social alcohol drinking, pregnancy, obesity, and well-controlled diabetes mellitus or hypertension. ASA III patients have severe systemic disease and substantive functional limitations, with one or more moderate to severe diseases. Examples include poorly controlled diabetes mellitus or hypertension, COPD, morbid obesity, active hepatitis, alcohol dependence or abuse, implanted pacemaker, moderate reduction of ejection fraction, End-Stage Renal Disease (ESRD) undergoing regularly scheduled dialysis, history of myocardial infarction, and cerebrovascular accidents.

ASA IV patients have severe systemic disease that poses a constant threat to life, such as recent myocardial infarction or cerebrovascular accidents, ongoing cardiac ischemia or severe valve dysfunction, severe reduction of ejection fraction, sepsis, DIC, ARD, or ESRD not undergoing regularly scheduled dialysis. ASA V patients are moribund and not expected to survive without the operation, such as ruptured abdominal or thoracic aneurysm, massive trauma, intracranial bleed with mass effect, ischaemic bowel in the face of significant cardiac pathology, or multiple organ/system dysfunction. Finally, ASA VI patients are declared brain-dead and their organs are being removed for donor purposes.

The contraceptive implant primarily works by inhibiting ovulation through the slow release of progesterone hormone. While it also increases cervical mucous thickness, this is not its main mode of action. The progesterone-only pill also increases cervical mucous thickness, while the intrauterine copper device decreases sperm viability. The intrauterine system prevents implantation of the ovum by exerting local progesterone onto the uterine lining.

Understanding the Mode of Action of Contraceptives

Contraceptives are used to prevent unwanted pregnancies. They work by different mechanisms depending on the type of contraceptive used. The Faculty for Sexual and Reproductive Health (FSRH) has provided a table that outlines the mode of action of standard contraceptives and emergency contraception.

Standard contraceptives include the combined oral contraceptive pill, progesterone-only pill, injectable contraceptive, implantable contraceptive, and intrauterine contraceptive device/system. The combined oral contraceptive pill and injectable/implantable contraceptives primarily work by inhibiting ovulation, while the progesterone-only pill and some injectable/implantable contraceptives thicken cervical mucous to prevent sperm from reaching the egg. The intrauterine contraceptive device/system decreases sperm motility and survival and prevents endometrial proliferation.

Emergency contraception, which is used after unprotected sex or contraceptive failure, also works by different mechanisms. Levonorgestrel and ulipristal inhibit ovulation, while the intrauterine contraceptive device is toxic to sperm and ovum and inhibits implantation.

Understanding the mode of action of contraceptives is important in choosing the most appropriate method for an individual’s needs and preferences. It is also important to note that no contraceptive method is 100% effective, and the use of condoms can provide additional protection against sexually transmitted infections.

Clinical Manifestations and Sequelae of Mumps

Mumps is a viral infection that commonly affects the salivary glands, causing parotitis, oophoritis, and orchitis. However, it can also lead to acute pancreatitis. In addition to these clinical manifestations, mumps can result in various sequelae, including meningoencephalitis, arthritis, transverse myelitis, cerebellar ataxia, and deafness. These conditions can occur as a result of the virus spreading to other parts of the body, such as the brain, spinal cord, and joints. However, disseminated intravascular coagulation (DIC) is not typically associated with mumps.

Phenytoin induces the activity of P450 enzymes.

The P450 enzyme system plays a crucial role in the metabolism of various foreign substances. Phenytoin is known to induce the activity of two families of P450 enzymes, namely CYP3A4 and CYP2C9. On the other hand, P450 inhibitors such as sodium valproate, ciprofloxacin, omeprazole, and fluoxetine can inhibit the activity of these enzymes. Warfarin is primarily metabolized by CYP1A2, CYP2C9, and CYP3A4. Therefore, the induction of metabolism by phenytoin can lead to a decrease in INR levels.

P450 Enzyme System and its Inducers and Inhibitors

The P450 enzyme system is responsible for metabolizing drugs in the body. Induction of this system usually requires prolonged exposure to the inducing drug, unlike P450 inhibitors, which have rapid effects. Some drugs that induce the P450 system include antiepileptics like phenytoin and carbamazepine, barbiturates such as phenobarbitone, rifampicin, St John’s Wort, chronic alcohol intake, griseofulvin, and smoking, which affects CYP1A2 and is the reason why smokers require more aminophylline.

On the other hand, some drugs inhibit the P450 system, including antibiotics like ciprofloxacin and erythromycin, isoniazid, cimetidine, omeprazole, amiodarone, allopurinol, imidazoles such as ketoconazole and fluconazole, SSRIs like fluoxetine and sertraline, ritonavir, sodium valproate, and acute alcohol intake. It is important to be aware of these inducers and inhibitors as they can affect the metabolism and efficacy of drugs in the body. Proper dosing and monitoring can help ensure safe and effective treatment.

Myocardial ischaemia can be caused by cocaine-induced coronary artery spasm.

Understanding Cocaine Toxicity

Cocaine is a popular recreational stimulant derived from the coca plant. However, its widespread use has resulted in an increase in cocaine toxicity cases. The drug works by blocking the uptake of dopamine, noradrenaline, and serotonin, leading to a variety of adverse effects.

Cardiovascular effects of cocaine include coronary artery spasm, tachycardia, bradycardia, hypertension, QRS widening, QT prolongation, and aortic dissection. Neurological effects may include seizures, mydriasis, hypertonia, and hyperreflexia. Psychiatric effects such as agitation, psychosis, and hallucinations may also occur. Other complications include ischaemic colitis, hyperthermia, metabolic acidosis, and rhabdomyolysis.

Managing cocaine toxicity involves using benzodiazepines as a first-line treatment for most cocaine-related problems. For chest pain, benzodiazepines and glyceryl trinitrate may be used, and primary percutaneous coronary intervention may be necessary if myocardial infarction develops. Hypertension can be treated with benzodiazepines and sodium nitroprusside. The use of beta-blockers in cocaine-induced cardiovascular problems is controversial, with some experts warning against it due to the risk of unopposed alpha-mediated coronary vasospasm.

In summary, cocaine toxicity can lead to a range of adverse effects, and managing it requires careful consideration of the patient’s symptoms and medical history.

Antiretroviral Therapy Options for Pregnant Women with HIV

The British HIV Association recommends that all pregnant women who are HIV-positive should be started on combined antiretroviral therapy in the second trimester and continue it lifelong. This therapy consists of three agents. Even if the viral load is low, antiretroviral therapy is still recommended.

For women who refuse combined antiretroviral therapy, zidovudine monotherapy can be offered if the patient has a CD4 count of > 350 and a viral load of < 10 000 copies/ml and agrees to a Caesarean section. This option is less effective than combined therapy but can still be considered. If zidovudine monotherapy is chosen, it should be started in the second trimester and continued until delivery. During delivery, a zidovudine infusion should be running. If the viral load remains < 50 copies/ml, a planned vaginal delivery can be considered.