Benign Prostatic Hyperplasia Case File

Benign Prostatic Hyperplasia Case File

Eugene C. Toy, MD, Lawrence M. Ross, MD, PhD, Han Zhang, MD, Cristo Papasakelariou, MD, FACOG

CASE 31

A 63-year-old male complains of a 6-month history of difficulty voiding and feeling that he cannot empty his bladder completely. After voiding, he often feels the urge to urinate again. He denies urethral discharge or burning with urination. He has had mild hypertension and takes a thiazide diuretic. His only other medication has been ampicillin for two urinary tract infections during the previous year. On examination, his blood pressure is 130/84 mm Hg, his pulse rate is 80 beats/min, and he is without fever (afebrile). The heart and lung examinations are normal, and the abdominal examination shows no masses.

⯈ What is the most likely diagnosis?

⯈ What is the anatomical explanation for the patient’s symptoms?

ANSWER TO CASE 31:

Benign Prostatic Hyperplasia

Summary: A 63-year-old male who has hypertension complains of a 6-month difficulty in voiding and the sensation that he cannot empty his bladder completely. He has had two episodes of urinary tract infections but denies dysuria (uncomfortable burning sensation on urination) or urethral discharge.

• Most likely diagnosis: Benign prostatic hyperplasia

• Anatomical basis for the symptomatology: Compression of the bladder neck or the prostatic urethra

CLINICAL CORRELATION

The prostate gland is the largest of the male accessory sex glands, and its secretions contribute to semen. This encapsulated gland is located in the pelvis, between the neck of the bladder and the sphincter urethrae muscle, and surrounds the first part of the male urethra, called the prostatic urethra. Enlargement of the prostate, benign prostatic hyperplasia (BPH), is a common condition in men 50 years and older and appears to depend on age and hormone level. A prostate-specific antigen blood test and a digital rectal examination (DRE) would be done to evaluate the gland’s size and the presence of nodularity, which might suggest carcinoma. Initial treatment after a confirmed diagnosis of BPH is often medical, with a medication such as a 5-α-reductase inhibitor, which relaxes the smooth muscle within the stroma of the gland and thus increases urethral diameter. Other medications block the effects of testosterone metabolites on gland tissue, resulting in involution of gland tissue. In advanced cases, a surgical transurethral resection of the prostate may be required. Although no direct relation between BPH and prostate malignancy has been proved, both conditions occur in the same age group.

APPROACH TO:

Male Internal Genitalia

OBJECTIVES

1. Be able to describe the anatomy of the internal male genital organs: ductus deferens, seminal gland, ejaculatory duct, prostate gland, and bulbourethral glands

2. Be able to describe the anatomy of the male urethral tract

DEFINITIONS

PROSTATIC HYPERPLASIA: Benign enlargement of the prostate gland that, because of the capsule surrounding it, impinges on the urethra

URINARY HESITANCY: Abnormally long period required to initiate a stream

of urine

TRANSURETHRAL RESECTION OF THE PROSTATE: Procedure in which the surgeon excises prostatic tissue from the prostatic urethra in an effort to relieve obstruction

DISCUSSION

The paired ductus deferenses traverse the inguinal canal and enter the abdomen through the deep inguinal rings, where they retain a retroperitoneal position. They cross the external iliac vessels and superolateral surface of the bladder, continue superior to the ureters entering the bladder (mnemonic: “water under the bridge”), and reach the posterior surface of the bladder, just anterior to the rectal vesicular pouch. The terminal portion of the ductus is dilated to form an ampulla of ductus deferens. Lateral to the two ampullae are the diagonally positioned, paired seminal(s) gland(s). These accessory sex glands produce an alkaline component of semen, which neutralizes the usual acid environment in the vagina. The duct of each seminal gland unites with the ductus deferens on each side to form the paired ejaculatory ducts, which course anteroinferiorly through the prostate gland to open on the elevated seminal colliculus on the posterior wall of the prostatic urethra (Figure 31-1).

The prostate gland is the largest of the accessory sex glands, an inverted pyramid about the size of a walnut. The base is located inferior to the neck of the bladder, and the apex rests on the sphincter urethral muscle. The prostate has a thick fibrous capsule surrounded by a fibrous sheath that is continuous with the puboprostatic ligaments. The levator ani muscle supports the gland inferolaterally, and the anterior surface is covered by fibers of the sphincter urethral muscle. The prostate is anatomically divisible into four lobes. The anterior lobe lies anterior to the urethra and is a superior fibromuscular continuation of the sphincter urethral muscle. The posterior lobe is midline, posterior to the urethra, and palpable by digital rectal exam (DRE). The lateral lobes on each side of the posterior lobe form the largest part of the gland and are also palpable by DRE. The middle lobe is the wedge-shaped superior portion of gland between the urethra and the obliquely oriented ejaculatory ducts and is closely related to the neck of the bladder. Enlargement of the middle lobe (as in BPH) causes pressure on the neck of the bladder. The multiple ducts of the prostate open onto the posterior wall of the prostatic urethra and constitute a major component of semen. The paired bulbourethral glands are pea-size glands embedded in the sphincter urethral muscle, posterolateral to the membranous urethra. The ducts of each gland empty into the proximal part of the spongy (penile) urethra in the bulb of the penis. Their mucous secretions lubricate the urethra during erection.

Figure 31-1. The prostate gland.

The male urethra is divided into four parts. The preprostatic urethra is a short continuation of the bladder neck. The prostatic urethra, the widest part, passes through the prostate gland, somewhat closer to its anterior surface. The posterior wall is elevated as a fusiform ridge called the seminal colliculus, on which are found the openings of the prostatic utricle (an embryonic remnant) and the paired ejaculatory ducts. The grooved portions of the urethra on each side of the colliculus are the prostatic sinuses, which contain the openings of the prostatic gland ducts.

The third part, the membranous urethra, is surrounded by the sphincter urethral muscle, or the external urethral (voluntary) sphincter. The fourth and longest part is the spongy (penile) urethra, which traverses the corpus spongiosum and terminates at the external urethral orifice on the tip of the glans penis. As the urethra enters the bulb of the penis, it widens to form the bulbar fossa into which open the ducts of the bulbourethral glands. The urethra widens again just proximal to the external orifice as the navicular fossa.

COMPREHENSION QUESTIONS

31.1 A 66-year-old man complains of difficulty voiding and is noted to have probable BPH. Which of the following prostatic lobes is likely to be responsible for these symptoms?

A. Anterior lobe

B. Posterior lobe

C. Lateral lobe

D. Middle lobe

31.2 A 48-year-old man is undergoing cystoscopic examination. As the cystoscope is placed into the urethra through the penile portion, which of the following tissues surrounds the urethra?

A. Prostate

B. Corpus spongiosum

C. Seminal colliculus

D. Sphincter urethral muscles

31.3 A police detective takes a scraping of some stains to be examined for alkaline phosphatase to assess whether these might be ejaculate. What is the source of alkaline phosphatase in the semen?

A. Prostatic gland

B. Bulbourethral glands

C. Seminal gland

D. Seminal colliculus apparatus

ANSWERS

31.1 D. The middle lobe of the prostate is the part through which the urethra traverses and may be obstructed by BPH.

31.2 B. The longest portion of the urethra is the penile urethra, which traverses through the corpus spongiosum.

31.3 C. The seminal gland are the source of the alkaline phosphatase in the semen. The alkalinity helps to neutralize the acidity of the vagina.

ANATOMY PEARL

⯈ The posterior and lateral lobes of the prostate are palpable by DRE.

⯈ The middle lobe may press on the bladder neck in BPH.

⯈ The sphincter urethral muscle extends superiorly to cover the anterior surface of the prostate.

⯈ The bulbourethral glands lie adjacent to the membranous urethra, but their ducts open into the proximal spongy urethra.

References

Gilroy AM, MacPherson BR, Ross LM. Atlas of Anatomy, 2nd ed. New York, NY: Thieme Medical Publishers; 2012:252−253. 

Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy, 7th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2014:376−379, 381. 

Netter FH. Atlas of Human Anatomy, 6th ed. Philadelphia, PA: Saunders; 2014: plates 361−363.

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